If those people bet the farm, then, yes, they can potentially "lose everything". People who bet the farm on anything, are foolish.
At its peak the other week, crypto made up around 8% of my portfolio. I took profits at least twice since then. Now crypto makes up about 3% of my portfolio. THAT is among the lowest percentage in my portfolio. One sector holds 59.5 % of my portfolio. Another holds about 31%. The others hold 4% and 2.5%. Obviously I do make big bets. But that has worked for me. But, I don't make big bets on crypto. And that's partly because I don't understand it that well. I depend on those who do to make my investments in that sector. I don't know how to fly a plane. But I trust those who do to get around. I'm aware of professionals who have 20% of their portfolio in bitcoin. Even if I completely understood it, I would not put in 20%. And that's partly because I understand very well the other sectors I'm in and feel comfortable with those allocations.
The thing about bitcoin is that it does not take a lot to make a lot. I don't remember when I first invested in crypto. I do know it has been years. And I do know I'm in the green in my crypto investments that I have made. So right now, what I have in the market in the crypto sector, is "house money". So even if you turn out to be right and bitcoin goes to zero, I will be fine, really fine.