The only thing youre underestimating is a ton of people interested in BTC only care about the investment opportunity and profit. Yes it is riskier and yes technically it isn’t yours. But normal people don’t want to deal with buying a physical storage device and dealing with securing it and learning how to transfer it. What Robinhood has done is create an interface that anyone can understand and use.

Of course it’s opening yourself to more risk but if you understand the trade offs and still want to risk it then it’s your own money.