If he had bought 1 BTC and sold it now when the price of Bitcoin was twenty thousand dollars, he would have made a profit of about 25K dollars even though he had paid a loan of 18K dollars.
Likewise...he has bought some BTC alone or after the last crash, whether with a small or large balance, it will not only cover your brother's debt of 18 thousand dollars but the investment may be enough to rest for a while and even that It can be used as preparation for retirement funds as well and is very possible.
In my opinion, maybe it was the influence of environmental factors that caused older brothers in your area to fall into this circle, whether there was a special invitation or whether they initially just wanted to try it. If he had used common sense and not followed the disregard I think this incident could have been avoided and would not have left him poor, neglected by his family in the end.