One possibility would be to keep up and coming competitor currencies from gaining a foothold. The big ASIC mining farms bitcoin has won't work with some of the

One possibility would be to keep up and coming competitor currencies from gaining a foothold. The big ASIC mining farms bitcoin has won't work with some of the smaller currencies. The organizations running them have a lot of money, and don't necessarily want to see competition from less centralized mining. Destroying trust in a currency by executing a double spend attack on it could be one way to prevent that.