There are plenty of old people buying lottery tickets.
All of these justifications are just an excuse to erect artificial barriers around the early stage market (aka where all the upside is). People should be free to spend their money as they see fit, even if that means shoveling it into a campfire.
Fraud and extortion are already illegal. It's totally possible to allow non-accredited investors access to early stage deals and continue to disallow fraud.
