That's pretty self-evident surely? What he wants to achieve is the investors having the information that they're being scammed - would you be asking "what are you trying to achieve" if someone was asking about telling someone that someone had just picked their pocket?
OP wants to inform investors that they're being defrauded because he sees it as the ethical thing to do - not everything has an ulterior motive. Sounds like he's wondering if there's any possible serious unforeseen repercussions that could befall him if he goes through with it (or doesn't). Losing the job (whether through quitting or getting fired for whistleblowing) is probably a foregone conclusion.
Maybe avoid criminal liability once the scam is uncovered? Even if you're just a regular employee, if you know about stuff like this and don't report it, you can be considered an accomplice...
In that case an anonymous report will not work to their favor: they should talk to a lawyer, get out ASAP and then consider their next steps carefully.
This entire post hinges on OP's correct interpretation that their employer is engaging in fraud against investors. This isn't as straightforward as defrauding customers because it's easier to judge fraud in sales because you probably don't know the exact terms agreed to as part of that investment. It's entirely possible the VCs are in on it or will try to kill the messenger rather than admit they didn't see the fraud.