no, they usually have a elaborate & consistent internal logic, based in assumptions supported by their social network that yours doesn't share!
they're just grounded in axioms/assumptions taken on faith cuz their friends believe it & leftists also necessarily do this all the time
it's cuz the people you trust believe it so you do too
you trust them cuz people you know do
the world is much too vast. we have to trust and we trust our support networks.
and also why left cults (and yes, there's a long and storied and sad history of left cults) prey on the marginalized and isolated, for the same reasons