Because taking high variance slightly negative EV shots is not a terrible strategy when you have a long time horizon.
I bought one lottery ticket, I don't think my odds are gonna get any better than that.
Of course you DONT want to repeatedly take -EV bets. That would reduce variance and converge you to the mean which is negative by the central limit theorem.
A strategy that works for a non-trivial amount of startups.
The idea is that if you play incorrectly long enough eventually a bigger better that's more wrong then you will come along.