It's only a gamble to a certain extent, for instance, even if her company fails, it's likely to happen in the next 2 or three years, that leaves another 7 or 8 years where she will require employment in order survive.

Judging by her character and drive to succeed (she emailed 1000+ angel investors, is starting her own business, etc) I could see her occupying a fairly high wage job, in the $50,000 - $80,000 range, if we take a mid point, that's about $65,000 per year for 7 - 8 years.

$65,000 * 7.5 = $497,500 / 10 = ~$50,000.

Assuming that's true, they only stand to lose half - if her idea succeeds however, they could make millions.

I would assume the investor isn't hard up of cash, so losing $75,000 would be a drop of water in the ocean, but making a few million would probably be a nice bonus.