No asset in the world can be protected on 100%. By wallets the most secure is hardware. As for the safety of bitcoin and its blockchain in a whole - it is considered that it can not be hacked, at least not yet.

From the point of view of cryptography, the block is sufficiently protected against such attacks. Quantum computers and quantum computing also do not pose a threat to hashing functions and the blockchain itself.
attacks by rebuilding the chain of blocks are real and depend on how well the shares of those participants who participate in the creation of blocks are distributed, where the shares can be measured both in computing power and other quantities depending on the consensus algorithm. The real danger is only short-term attacks on the last few blocks of the chain. To avoid risks, you must wait for a certain number of blocks to stabilize the chain. From practice for Bitcoin it is enough to wait for 3 blocks.

Availability of the finished product, or at least a clearly and clearly outlined strategy.
Hype and investors' trust.
Team/developers/advisors and their qualification.

I do not think that this is a suitable strategy. More than once already it was said that it is better to split assets. It's simple - minimizing risks. Bitcoin certainly has a leading position in most investors portfolios, but altcoins, should be too.

My country has the richest resources, huge mineral wealth, and huge investment prospects. But a corrupt government, a tense external economy, and a low salary level  - are depressing our economy. But very positive views on the cryptocurrency.

If a price increases or decrease smoothly - this happens when players are able to buy bitcoins.
If the price falls or rises sharply - it's a simple pump.

Bitcoin has three main problems: security, liquidity and profitability.
Based on this bitcoin does not fit the description of the reserve currency, although its popularity among investors is growing - many believe that bitcoin will soon come out of the shadows and take its rightful place among other currencies. But will be it global currency - big question.

On the one hand, the bitcoin concept is directly opposite to the concept of statehood. But no financial, exchange relations should not remain without regulation. Without any regulation there will be just chaos, and the number of scammers will be many times greater.

Binance is faster, easier to understand, all intuitively clear, new coins are listing almost every day. These are the main advantages. But Bittrex should not be forgotten, since it has many coins that are not listing on other exchanges, including the Binance. So, use both.

Ponzi scheme or pyramid - a form of investment fraud, which includes the payment of expected profits to existing investors from the funds collected from new investors. Organizers of the Ponzi scheme often attract new investors by promises to invest the collected funds in projects with a high return on investment and minimal risk. In many Ponzi schemes, instead of full-fledged investment, scammers are engaged in attracting new funds through which they will make promised payments to early investors and assign a portion of these funds for personal use.
The pyramid vanishs, because it becomes unprofitable to the beneficiary.
Bitcoin does not fall under the definition of the financial pyramid. This is, in fact, a form of digital currency that is used by network participants, and the number of virtual wallets for its storage today already exceeds 11 million worldwide. There are many factors that form the price of the currency, but one of the main is the volume of demand for the currency and the number of users it is of currency. Therefore, it is quite natural that with the expansion of the user network, the bitcoin price continues to grow. This is natural for any currency, and bitcoin should not be considered a particularly suspicious anomaly.

There are predictions, but there are expert estimates. And between them is a big difference. Predictions - intuition, expert research - analytics. So do not predict the future and believe in it. ICO market is still too young and yet in a trend, and while people are ready to invest, it will not go anywhere, certainly not in six months.

I am always amused when I read information that one or another new, unknown, "extraordinary" shitcoin will beat bitcoin in the coming year. Are there really those who believe this bullshit?

There are no trusted applications for the iPhone or iPad for mining. For Android users, there are more apps. Of course, there is no any competition with platforms on video cards, and even more with ASIC. Because of a weak processor, weak video card, fewer cores, heating, heavy loading, and charging. And financially it is not so attractive. Such mining is only for the mining, and not for profit.

To be honest, it can be anything. Despite the ups and downs - there is still no good alternative. No altcoin has even approached the volumes of bitcoin. I think in the coming years bitcoin will definitely not give up its leading position.

This is not only risky but also dangerous. Of course, it is better to split an asset (no matter of investing amount). The market is too volatile and unstable. And despite a large choice, you can minimize the risks, and give preference to more stable alts. Even if it's only $500, 50% for bitcoin, the rest is for alts.

In truth, all the altcoins are a kind of bubble and they are all overvalued
In general, as far as I know, the contract for the development of the Cardano platform was concluded until 2020. And so for today it isn't possible to say exactly whether Cardano will achieve the heights promised by its creators.
So it seems to me that ADA while drifting.

I see several reasons
New players come on Bitcoin market - institutional traders who had long planned to enter on short, because they did not see any fundamental strength or significance in Bitcoin as a currency or Bitcoin Network as a payment system.
80% of Bitcoin's turnover belongs to only 3 countries - South Korea, Japan and Vietnam(yes!) You must list countries to limit the turnover of funds in the country, and it is really problematic for people to buy an even dollar. They transfer their capital (dongs, yens, wons) to the cryptocurrency, in order to be able to not depend on the country's economy.
When rumors appeared a possible crypto-currency ban in South Korea, as well as on the new law, which obliges large miner pools to move out of China - the market reacted instantly.
Following the bitcoin, many altcoins dropped too and, of course, his forks. This phenomenon calls correlation. So this is nothing more than the actual dependencies of the main altcoins and forks from Bitcoin.

It seems to me that they do not really need it. ICO and cryptocurrency maintain the use of blockchain technology.
Does it need for usual messengers? The answer is obvious - no.
On the good and for telegram it was not necessary, but the trend required.

It seems to me the main reason why the state loses cryptocurrency is the loss of control over the economic sphere. Since the nature of bitcoin is contrary to the nature of statehood.

Theoretically, such a cryptocurrency, or altcoin, which would be better than bitcoin, may well appear. And in terms of functionality, let's say such it's blockchain will solve the bottlenecks of bitcoin blockchain. Such new altcoin would be more interesting for investors for many reasons. I'm not saying that it must be in future, but it rather possible.
And such altcoin could control market.