Make them feel heard, stop mocking them, agree that their gripes are legitimate or that the issue that needs to be addressed is legit. Talk about their concerns at length, in public, in a serious and understanding way.
Nobody should be coerced into sex, obviously. But whenever there is a mass shooting attributable to Islam/neo-Nazi/mental-illness/white-supremacist/incel/racism etc., it is totally nonsensical for society to say “We’ll ignore or mock it and the issue will go away on its own.”
Saying “these people should go seek help” isn’t the solution, either - people who are angry don’t think, “I’m angry, therefore I need to get help”. They think, “I’m angry, therefore I need to take out my rage on what makes me angry.”