The answer should be displayed somewhere on the site. What does the claiming page say?

It will if bitcoin raises in value and usd loses its value at the same time. Second is already a fact as inflation push prices up, thus 1 usd is worth less now than 5 or 10 years ago. But bitcoin needs also to raise its value. Possible, but we need to find a quick solution to network congestion and high tx fees.

Fully agree with you, 2017 was full of unpredicted events. Even the bitcoin price at the end of the year was unexpected.
One thing is sure, is that 2017 brings bitcoin  in the front scene, with more and more people interested in crypto. Will it push bitcoin to the top or will it make it crash in 2018, no one knows.

Depends on people and many factors :
1) faucets don't pay much, but it's totally free (no investment) and some only takes a few seconds to claim each time. It's a good bet if the coin price is expected to go up significantly in the long term (those who kept their bitcoin faucet earnings for a few years until now have actually some coins)
2) Trading may be profitable,  but minimum knowledge of the markets and time investment are required to get every news that could change price. You also need to invest to trade at the beginning.
3) mining isn't that much time consuming (once everything is settled it goes on by itself) but requires a big investment to buy material
4)article writing or signing campaigns is a good way, not too much time consuming but rewarding.
5) investment in bitcoin is not very profitable. The only sure place I know to invest is freebitco.in and its 4% annual rate. You can also lend to people, but beware of scammers.

The problem here is that the negative trust rating were all in the "untrusted feedback" section, hidden by default for users. Trust = 0 under profile and no "trusted feedback".
Always check trust by clicking on it under profile name, and ckeck also untrusted feedbacks. In your case, many were already scammed buying him some altcoins, so this should have warned you about the kind of user he is.

If bitcoin becomes worthless one day, there won't be any miners left to mine the remaining coins, would cost more than it would reward.
This is the worst scenario, but not impossible.
In a better future bitcoin still has value and will thus still exist in 2025 (technically bitcoin will exist in 2025, even if worthless). If we believe in bitcoin we can suppose it'll have more value than today and will be used worldwide as a currency.

It seems very hard to reach 500 k$ at the end of the year. An as good 2018 year as 2017 would bring bitcoin to 150k$, 500$ is quite a step further.
It may be possible in 3 years, but reaching this price level also means usd will lose in value, possible if bitcoin is spreading as a useful and used currency.

You should first do a proper report following this thread : https://bitcointalk.org/index.php?topic=260073.0
Then a trusted member will leave a negative trust on his profile.
But don't expect scammers to be banned here, it is not the case. Many scammers are spotted for weeks, but still continue their scam activities.

There are some days like today where every crypto are going down. A mere correction, I think, nothing to worry about so far.

No, and I won't do this, because btc investment is a risk. If btc value crashes one day, I won't be able to refund the loan I've done to buy btc. It's like people who sell their house or quit their job for btc, it's too risky.
Only invest what I can afford to lose. If I don't have money to invest I won't borrow some.

My goal, the same as op's one, to get a full bitcoin in January... 2020, maybe. Won't reach it before, unless I win a lottery.

If the bitcoin grows in 2018 as fast as it grew in 2017 then it could reach more than 150k$ at the end of the year.
But for now bitcoin is slowed by congested network and high tx fees. Price will raise significantly once those problems are settled and once bitcoin is able to be used by many more people worldwide.

Actually, you have 1/20000 probability to hit 10000,  not 1/10000. As the number calculated with player and server seeds is rounded, only the ]9999,5-10000] interval leads to number 10000, this interval is 1/20000 of the total [0-10000] interval.

Answered yes, keep my fragment of a bitcoin so far, even if its price is stable. I hope bitcoin will be more used in the future so that I can use it directly to buy goods instead of converting it to € and pay taxes.
By the way I don't believe bitcoin will remain stable very long...

Negative trust and locked thread to avoid bad comments from his victims. Why did you ever had the idea to trade with him?
Btw if you want to report a scam, you have to read this thread : https://bitcointalk.org/index.php?topic=260073.0 and give everyone evidences of the scam.

Have a look here : https://bitcointalk.org/index.php?topic=260073.0 before reporting a scam. Without proof, there's nothing we can do for you.

Investing in bitcoin is a risk, as the value can crash tomorrow.
I'm holding too so far, I believe in what bitcoin represents, so I'm taking the risk. Don't invest more than what you can afford to lose however, but if you can, you should buy more.
Also have a look in other cryptocurrencies.

It's possible if bitcoin improves itself to solve its current problem (but lightning network is on its way).
If more and more people believe in bitcoin and use it, its value will go up, and at the same time dollar value will go down faster than now (inflation), thus bitcoin price will reach 100k$.

Yes bitcoin can become worthless the day no one will buy it anymore, because it wouldn't have reached its purpose or because another currency will do better what bitcoin was first created for.
But bitcoin has the ability to evolve, we saw it recently with the first successful lightning network payment. So bitcoin still has value and will have more in the future.

When I was gambling I made an excel sheet that calculates how much I can win and lose with a martingale strategy. Inputs are initial bet I, odds O and % of bet increase in case of a loss P.
O variable determines chances of a win/loss, for example with O=2 at freebitco.in win probability is 0,475 and loss probability is 0,525. With a smaller house edge, win probability is higher, but still strictly smaller than 0,5.

I tried many combinations of I, O and P to see the most profitable. And conclusion of all this is that whatever the choices of I, O and P, if winning probability is strictly smaller than 0,5 (for O=2), i.e.if there's an house edge, then you're guaranteed to lose money in the long term, because every winnings at turn n and smaller won't cover the money lost at n+1 losing turn.