Probably yes. Can it handle the first 1000 users? Then, just create and ship your product before worrying about scalability.
Indeed. It's better to discover if your product fits the market before trying to do the extra 80% of the hard work. If it fits, you have data to confirm, and you can go to a money raising round with solid information. If it doesn't fit, you can get out of something that doesn't matter quickly.