How do you stop one noisy user from ruining your feature roadmap?

We fell into the trap early on of treating every angry feature request like a top priority, only to watch those exact users churn right after we built what they asked for.

We realized we were wasting weeks of engineering time building custom workarounds for individual edge cases instead of solving core issues that actually scale. What quick filter or rule do you use before agreeing to build a user-requested feature?