I bought once and the price went down too much.
That was my worst 'mistake' i would say.
But in your case i would think that you learned something and we should 'predict' if the price will go up or down.
For now bitcoin is only rising rapidly and it is going to reach soon $300.
It s going to reach 1k again, before the next halving. I dont see how buying BTC could have been the worst decision of his life. Unless he purchased those at $1200.
If buying BTC is the worst decision of his life, he has a pretty damn nice life!!!!!