Interestingly I'm in a similar situation. I'm working as a quantitative analyst (quant) at a big bank and I'm on the precipice of leaving. I am also dismayed at the possibility of having my salary cut in half. For this reason I'm strongly considering doing some sort of startup - I just need to figure out what to do :)

Even though I'm young, I'm realizing life is just too short to be stuck doing something you don't like. Make the switch or else you will regret it in a few years.