>How much would you have invested

Only what I could have afforded to lose. Around $5k. Not a lot of money (maybe even too small an amount to overcome the friction of traditional early-stage fundraising), but I would have gotten a much better RoI than my indexed stock-market fund got.

>and how well would you have done had the start-ups went belly up?

Well clearly I would have done poorly in that case. But that is why I don't invest more than I can afford to lose in risky investments.

"but I would have gotten a much better RoI than my indexed stock-market fund got."

Are you sure? How many stories have we heard here about people being diluted to shit when big investors come in?

Don’t know why this is being downvoted. The above comment makes it seem like early stage venture capital is an easy money spigot, and the only barrier to them getting rich is the big bad government.