Falling for a cult is something that can happen to almost anyone. I think it's somewhat healthy for one to recognize they were in a cult and to share the experience of realizing that and getting out. It may come off as smug, but it's also a pretty vulnerable thing to do as you are admitting "I was duped".

The main smugness one can have is thinking they are immune to falling for a cult. Lot's of people do for lots of reasons. It's particularly likely when someone is in a vulnerable position in life (death, depression, major life change). Sometimes people are simply born into the cults and realize later that everything their family and community believes is a lie. Regardless, cults are pretty good at finding and "loving" people into the cult.

All this is to say that everyone should take a moment to question their core beliefs. Why do I believe this? Could I be wrong? How would I know I'm wrong? Questions I know I wish I asked and explored earlier in life. The honest answers, though, can be devastating if this part of your identity or family identity.