While there are surely FOMO investors in any ICO, there's a really rational case for Tezos. It potentially solves the governance issues bitcoin had as well as offering provable smart contracts, which helps alleviate the constantly-hacked problem with ethereum smart contracts. In terms of the amount raised, I invested because the coldly rational math of what a market-cap competitive with wither of those would mean for the token value gave really great pot-odds to a "donation."

This was the first project I ever saw where the developer pitched the source code to hacker news fore review, rather than a whitepaper to a coin sale.