People fall for scams/cults/MLMs for all kinds of reasons: because they're bored/lonely, because they're in a bad place in their life, because they put their trust in a person they shouldn't have, etc. Not just because they're idiots.

My personal belief is that the best way I can set myself up to fall for a scam is by incorrectly believing that I would never fall for one. "Pride goeth before the fall." That's why I try to remind myself I'm as fallible as the next human.