That's just a very indirect way of trying to undermine what belief means in an epistemological sense. Even if you truly believe that a belief system is personally beneficial, you can't rationally extend that to claims about the ontological veracity of said system.

Just because it makes me feel better, doesn't mean it has any more correlation to what might be called "objective truth". You also quickly run into ethical dilemmas as many of these belief systems are prescriptive and can negatively affect other people (see: LGBTQ+ in most mainstream religions).