If you have great potential co-founders who are psyched about their idea, run with it right now. (1) As has been said many times, having 100% of a small market

If you have great potential co-founders who are psyched about their idea, run with it right now. (1) As has been said many times, having 100% of a small market is more attainable than having 1% of a huge market. (2) If they think the business prospects are amazing, that's great motivation for them. (3) Boring is good for startup success. The last field you want to compete in is the one everybody's excited about. If the idea flops, drop it and do something else. If it works, use it to bootstrap your next idea.