Are those other employees getting paid? Then there's nothing to worry about.

Equity is a gamble and should be treated as such. Most jobs don't contribute any value in the grand scheme of things beyond shareholder value, so that's not a loss either. If anything it's a learning opportunity to not trust startup founders so blindly.

But if you want to warn your coworkers out of comradery, do so in a way that isn't simply telling them "I think our boss is defrauding investors".