Even if you match their level of polish (which is nearly impossible due to manpower), why would someone use an unknown service over theirs? I think this follow

Even if you match their level of polish (which is nearly impossible due to manpower), why would someone use an unknown service over theirs? I think this follows the other reply: you should offer something different that's attractive enough for a client to pick your service over theirs. Something you enable or focus on that Stripe can't. Usually this happens because they'd have to sacrifice the experience of a much larger group of clients or your niche is too small to be worth it for a team at a bigger company. The bet is that serving this new group/need will help you a)end up with a profitable group of customers that grows and/or b)end up developing a user-base/feature-set that makes it easy for you to expand to other users/products and steal market from the bigger competitor.