You may not want to hear this, but you just answered your own original question: you lose interest because you don't care.
I can't imagine "snubbing" anyone, much less my own customer. And I know lots of people that would give almost anything for a customer. You may not realize it now, but the "pushy" customers are the best ones, especially when you're first starting out.
Go pursue some other passion. Leave the start-ups for those of us who really care about the people we service.