Given the number of companies exit at 100m vs exit 1-99m is huge. They're taking a bet at the earliest possible time and are only making money in the case of extreme success.
It's a 75:1 return on investment for those that make it to a 100M exit. They just need to make sure that they can pick better than 1 in 75 to break even. If they can get 1 in 25 they'll get a 300% ROI. If they can get an exit within 5-10 years, then that's very competitive against other investments.