Every single thing in life is base on faith. Even basic necessities like bread. The price is based on the expectations and fears of all of us.
Bitcoin is no different, which is great. If bitcoin was different from normal investments I would be truly worried.
Just diversify and you will be fine.

The OP might be asking about how to manage bitcoin as an investment.
You should diversify. Use various cryptocurrencies as well all normal investments like stocks and bonds.
All instruments have risks so you should create a portfolio that best reflects your risk/reward expectations.

All markets, including cryptocurrencies, have volatility. All markets depend on faith. There isn't a company or resource behind bitcoin so there is no wonder there is volatility.
There are ways to reduce volatility: for example, invest in more cryptos or even invest 60% in stocks and 40% in cryptos.
It's extremely weird for any rational person to be surprised about volatility.

This argument again? Bitcoin is just a currency. Criminality will always exist. Even if they ban bitcoin criminals just move to cash.
I don't think any government really blames bitcoin or any other payment method for criminality. This argument keeps popping up all the time, but it makes little sense.

Investing is not about Bitcoin at all. Sure you can hear these stories about bitcoin, but you van hear them about penny stocks as well. This is not a new phenomenon. The important thing is that you keep you risk to a minimum while you keep your profits.
This mentality has nothing to do with cryptocurrencies. Just keep diversifying,

Even if you are only thinking of bitcoin as a currency you should still encourage investors because they are te ones who keep increasing the price of bitcoin. Which is good for everyone. increasing price just increased awareness and interest in Bitcoin which is the most important factor.

I would not spend my Bitcoin at all. It is obvious tat it will increase in price. If not Bitcoin some other cryptocurrency. I would just keep it for as an investment.
The stores that accept bitcoin seem to increase exponentially, so I would simply wait.

Cash is better because there are no taxes for exchanging currencies, but there is a tax on buying Bitcoin in many countries. Also, Bitcoin can also be classified as an investment which means you have to pay taxes on your gains, but in most countries, you can't compensate a portion of the losses from your taxes even tho it is available for traditional investments. Just something to think about.

Keep in mind that you don't actually have to buy Bitcoin to benefit from the price movements. There are plenty of brokerages that started offering Bitcoin CFD-s. You don't actually own BTC in that case but you gain or lose money the same way if you would. The advantage is that most brokers are regulated in comparison to most Bitcoin wallets. Also, liquidity is better for brokerages and it doesn't freeze like Coinbase tends to when you need it the most...

There is no possibility for the USD to fall. Nearly every currency in the world uses the USD as it's exchange reserve, which means everyone is holding an immense amount of USD, therefore buyers/holders will always outnumber sellers. If no one sells USD it's price won't fall aside from the usual volatility thus making it invincible
https://en.wikipedia.org/wiki/Reserve_currency

What is the point of holding Gold? Gold is simply hedging out the Sock market. If the stock market does well Gold will stagnate. If a financial crisis hits everyone will buy gold. No point holding Gold until that point in my opinion.
Did anyone who said holding gold is good actually looked at a gold price chart? Gold doesn't even track inflation which means you are loosing money if you invest in gold long term. If you want super safe investing either invest in low yield bonds or peer to peer lending.

Bitcoin is a direct competitor for Paypal. Obviously, they want to delegitimize it so you can't trade it officially.
That being said PayPal doesn't care. If you don't explicitly tell them the transaction is about Bitcoin even if a human looks at your transaction in a dispute they won't care. Best reason to give is no reason at all.
If someone charges back a PayPal payment for Bitcoin it is literally not possible to fight that.

All technical indicators are NONSENSE. They work because people AND bots are using them. If the first book about technical analysis would have sad that when the sky turns red sell sell sell then that would be technical analysis. If enough people start using an indicator it will work. That's all.
Using that logic use the indicators that are most popular. Support and resistance come to mind right away and seems to work everywhere.
The usefulness of the other indicators depends on the market, but once again only because people are using them more in those markets.
The best strategy is to wait until the price drops. Wait some more until it stabilizes on a certain level. Then buy, but use only a part of your capital and add more as the price moves favorably.
At least this worked for me before.

I think your math is wrong.
Should be
30*100+50*50=5500
Even that is only 0.15 USD.

It seems to me that rather than the price of Bitcoin falling it will simply stay at the 2-3k range when another cryptocurrency takes its place.
Bitcoin established itself as the go-to currency to fall back on from riskier investments. For that reason alone it will keep at least some of its value.
Not to mention this is the most publicized crypto which means a lot especially for people who aren't as involved in cryptos as most people here on Bitcointalk are.

It doesn't matter when you buy. You should make a profit given enough time. Those who bought at 2800 at the end of the bubble will make a profit at some point as well (if they long enough that is). The worth thing that you could do at that point is selling at 2200. Now we are at 2500 and we will reach 2800 at some point.
Past performance proves that entry point doesn't matter at bitcoin because it just keeps rising. A general rule is to buy the dips, however, if you always wait you will never buy any Bitcoin...

I don't like trading that much. It is soo easy to get greedy and overcommit and loose money. I never lost money doing ait due to being very conservative with my trades, but I can feel the intense psychologcal pressure that comes with it. Some people like it some don't. I prefer to invest long term.

I don't think it will ever end. If it as only Bitcoin I would say 2-3 years, but there are so many cryptos and such innovation that this might continue until an even better technology comes along or we reach utopia without any currency.
Even in 5-10 years radically new cryptos can come out creating dynamic markets as it is now.

Just to offer a different point of view. You are investing your money even if you do nothing. You invested it into inflation so you get a negative return on your investment. Not investing your money also have costs due to inflation and Forex risk. Not to mention the opportunity cost.
If you are paranoid about losing your money choose investments which are extremely safe. Bonds, mainstream Stocks, collateralized lending, add 40% gold to your portfolio and it will be impossible to lose money even if the stock market collapses wince Gold hedges out the stock market.

You can make money with anything. Is Forex the best choice? I don't think so. Highly volatile and you need to use extreme leverages to catch the price movements. You can wipe out your entire investment within minutes.
I think there are much better ways to make money. Like trading with real products, opening an online service or investing long term.
Avoid Forex if you can. I did it all and you will only succeed if you are either extremely lucky or devote your entire life to it.