I don't really believe the "if you're young and conservative [...]" quip, but there does seem to be a lot of evidentiary weight to suggest that it's okay to have a Libertarian phase when you're young, but only as long as you grow out of it. (As opposed to evolving into a fascist.)
At some point I think everyone needs to develop a bit of selfishness as part of their growth, but getting stuck into an ideology like promotes it as the end-all like Objectivism is a massive trap to prevent further growth.
Feeling relieved to remember that someone recommended The Fountainhead to me, and I gamely got through it, but had already noped out because the protagonist marries her rapist. Nothing else could overcome that for me ideologically. It was all fruit from a poison tree, to 15yo me.