I mean, this has scam all over it, but if they're really willing to keep paying her small amounts for small tasks, couldn't she just prove the concept first, so she could say look, I invested 3K, and now I've earned back 3,500 and counting, so it can't be a scam. She could then put in more money.

That won't happen, of course, because it doesn't make sense that they'd make her put in her money in order to get a job doing little make work tasks, but could you pitch it to her as a compromise?