> Investments are sound based on probability and risk beforehand.
Investing in bitcoin had a limited downside (lose 100%), but a very high upside (reaches it's initial goals). For me, the potential gains outweighed the low probability.
I consider myself very lucky that I made some money (wasn't crazy to put all my money in there). But for me, when it would have gone to 0, I still feel it was worth the risk.
But of course, with such a high risk high reward investment, only invest a small % of your total money.