If someone gives a shit about this, they’ll find a way to avoid Stripe. This might surprise you because you’ve presumably have never given enough of a shit about a cause to actually modify your behavior for it, but deciding to participate in a boycott does in fact mean having to sacrifice your own convenience and limiting the options available to you.
The customer is always right. In the original meaning of the phrase: if enough people are sufficiently mad at your business to stop spending their money for your services, you as the business owner are in no position to argue with them or call their concerns frivolous.
No business owner is being forced to acquiesce to the boycotters’ demands. People are just choosing not to give them money if they don’t like what they’re seeing. If a boycott like this ends up tanking Stripe or any business that uses it, that’s literally the free market at work and the result of consumers exercising their right to choose who to do business with. Tough luck, should have adapted to the market.