People are terrible at assessing risk, especially when it's not their day job. Even when it is their job, assessing risk in an adversarial environment is an extremely difficult thing.
Your dad (not really your dad, but for sake of example) is a retail investor. He has no idea what he's doing, but he heard "through the grapevine" that he should invest in this one particular startup. He sends them his IRA balance.
A year later the startup exits, but he hasn't been paying attention and turns out he's been diluted to 10% of what he thought he had. Now he has nothing.
The craps table is marketed as a gambling game and has a published payout figure. Startups crowdfunding for equity usually have a slick pitch video about how this excellent opportunity to tap into a £1bn market is a great investment.
An opportunity which for a retail investor with adverse selection problems and no influence over company decisions is likely a vastly worse "investment" compared with a game of craps (the expected return on craps is probably less negative and the probability of at least breaking even is certainly higher at the craps table)
And people comparing crowdfunding with "regular stocks" - even on here where it's well known most startups fail - are prime example of which the public in general doesn't know enough about investment to consider it...
Every single one of those has substantially more regulation about what they can do with how much of his money, and what they must and must not say when they do it.
I'm not at all sure all of that makes sense, but it's a huge difference.
Your dad (not really your dad, but for sake of example) is a retail investor. He has no idea what he's doing, but he heard "through the grapevine" that he should invest in this one particular startup. He sends them his IRA balance.
A year later the startup exits, but he hasn't been paying attention and turns out he's been diluted to 10% of what he thought he had. Now he has nothing.