Are we all in agreement that this is an attempt to raise cash from poorly informed greater fools? They disguised it as a bonus, but in reality they're hoping to get people buy in to their failing company?
No. Not exactly. You aren't exactly "buying in" until you choose to exercise the warrants.
There is a long history of companies selling notes with warrants attached. Prosper is selling notes to investors, so it would seem that this falls into an old pattern with which the SEC is familiar. That's probably smart from a regulatory point of view.
As for the "poorly informed greater fools", Prosper has provided a prospectus, per SEC regulations etc. If this prospectus is good enough to inform investors who buy notes, then it should be good enough to inform investors who buy notes with warrants attached.