Thinking about potential problems with an exit before you've even started building something is frankly ridiculous. Just start. What anyone might buy in a few years time if you're successful will be very different to what you build now because you will learn things about what the customer wants along the way. Whether that's shifting to a more appropriate language is something that only time will tell.
Completely agree. Remember, PG and team wrote Viaweb in Lisp because that is what they were comfortable with. They got acruired by Yahoo because they had the users and the best product in the market. The fact that it was built in Lisp did not deter Yahoo at all.
Stackoverflow is built on .Net and nobody is questioning that now.
It could turn out to be an advantage that the others keep writing you off as 'destined to doom' because you are on the .Net platform.
