Ayn Rand preached atheism, as part of the all-encompassing cult-like philosophy of life she invented (“objectivism”), and her books were meant to convince people to adopt her warped worldview. Her books exalted ruthless selfishness as the highest value, and displayed utter contempt for poor people. Much like Nietzsche, she meant to turn Western Judeo-Xian values upside down.
I think it’s highly inappropriate for a Jew to read a book by a someone (particularly a Jew like Ayn Rand) who invented and evangelized for a new atheistic ideology. However, I’m not surprised that some read her anyway, since its politics coincide with some people’s right-wing economic views.
People have every right to conclude that conservative economic and welfare policies are better — even though, at least in Israel, you’d be hard-pressed to find any gadol supporting right-wing economic policies like cutting welfare and such — but they shouldn’t conclude that then any author who shares such views is kosher.
Perhaps many people enjoy her writing, but it’s also commonly observed that reading her books tends to warp people’s personalities, making them less kind and pleasant and more ruthless and cruel. I’ve noticed this personally in people I know. It’s often temporary, but not always.
I’m not concerned about her advocacy for legalization of drugs. It’s a genuine empirical question whether making drugs illegal causes more harm than good. I’m not aware of Chazal showing any interest in banning or restricting certain substances and throwing people in jail if they disobey.