"If we don't, someone else will" is not an ethical get-out-of-jail-free card. Literally anything will happen in a capitalist market, if someone is willing to pay for it. Does that mean everything that someone will pay for is ethical and you shouldn't bother trying to abstain from it?

If you want to be pragmatic about it, the fewer people who are willing to do X, theoretically the higher the price goes, possibly to the point where no one wants to pay to do X anymore. So refusing to do X is not just an empty gesture.