Why on earth would they give those sweet pre-IPO shares up to the unwashed masses if they thought there was even a remote chance the IPO would at least break even?

I suspect it's because they're worried that their users are going to short them and encourage others to do the same, so they're trying to get them involved and committed. They don't want WSB causing shit. My guess is that the share prices will do pretty well, at least initially. There are plenty of ignorant investors who want to get in on the next big tech stock. Just a guess though, I don't know enough about this stuff to invest in stocks myself.