Despite having had the relevant experience, I've always found it hard to understand why this happens.
You know you're taking a drug that reliably induces feelings of "oceanic connectedness". Why should you change your worldview as a result? All kinds of things can change the way you feel temporarily, but most of them don't leave you thinking that you got insight into the way things really are.
Maybe it's that psychedelics also induce feelings of having discovered something important, and a lot of people don't try to double-check whether they actually did.
You know you're taking a drug that reliably induces feelings of "oceanic connectedness". Why should you change your worldview as a result? All kinds of things can change the way you feel temporarily, but most of them don't leave you thinking that you got insight into the way things really are.
Maybe it's that psychedelics also induce feelings of having discovered something important, and a lot of people don't try to double-check whether they actually did.