One of the beautiful things about buying bitcoin right now is that there is NO NEED to go all in! It is such an asymmetric bet, that in a truly ridiculous upside scenario, investing even a small amount at today's prices will make you very very wealthy. If you invested 5% of your net worth, and bitcoin went up 100x, you'd be 84% in bitcoin at THAT point, but at that time, it would actually be a much safer holding by virtue of the implications of its successful history.
There are a lot of unknowable risks still lurking out there. At this time, unless your net worth is extremely low compared to your salary (i.e. you're young and you basically haven't saved much), going all in is just a recipe for panic-selling when the inevitable volatility rears its head. In general, if you can't sleep at night because of your bitcoin holdings, you have too much invested.
I fully agree with first part. I might be wrong but I think it is not responsible for a young adult with a job and without any savings, neither. Because that's his primary goal is to build up savings/secure capital. Going all-in in bitcoin means he will also lose all his capital if it fails. Why do you make an exception for such person? I also have a part that wants me to go all in so part of me would be very happy if you could give good reasons why it does not apply to such person.
Maybe people dont want to support the current system at all as they see it as life destroying for the planet ?
Even gold mining causes devastating environmental issues. The best investment you can make is learning how to grow your own food etc.