What's the actual meaning of "If you don't develop schizophrenia by 30, you most likely never will?"

[Napier]

@Velocity

born with the inner schizophrenia time bomb but as they reached age 30 their brain gradually “hardened”

I wasn’t really going for this effect.

@LSLGuy

morons who wrote the aphorism & popularized it didn’t actually understand how to write unambiguous sentences

Yeah. This is it.

@griffin1977

schizophrenia usually develops before 30

If at all, yes. I think this is what somebody was trying to express, though they made it more complex and put it off the mark.