Well, I'm neither a believer nor a non-believer. I'm agnostic.
But I *did* spend some time in a monastery in my mid 20s [I had
convertitis to Eastern Orthodox Christian] - and one night I
'got' the Trinity thing. Had similar experience with QM but that
was as a teenager doing a book report.
Once it makes sense, it makes sense. Doesn't have to be true for
me, just comprehensible.