Having been close friends with someone who’s way into astrology, I think there’s a number of factors here.

Firstly, in a world that is clearly ‘going wrong’, with ever increasing economic precarity, political polarization, and visible worsening of climate change, the idea of a system than can give you any level of prediction for your personal future is a huge comfort. Marxism, despite being a scientific discipline that makes very accurate long-term predictions of social development, has no (or very little) power on the individual level, so some people may cling to this other system that gives them a sense of preparedness for their personal life. And while I agree that truly understanding and internalizing a dialectical-materialist perspective means both an end to being able to believe in things like astrology, and a kind of inner peace in the face of the inevitable dialectical unfolding of the material world, most people (who are still valuable allies) never actually reach that level of understanding.

Secondly, as people are increasingly alienated and atomized, it provides access to a large social space of overwhelmingly non-straight-white-cis-male people, immediately gives you a tribe with specific traits and icons to identify with, has (at the very least, the aesthetic of) a deep history going back to antiquity and has a lot of specific in-jokes that can quickly bring someone into the fold. My friend is constantly posting memes about the supposed characteristics of various different star signs, sub-categories of those star signs, interactions between different star signs, etc. etc. It’s an endless source of, for want of a better word, content, which you can enjoy both as part of the space as a whole and from within your specific niche. You can see something and say “Yes, I am like that! They know me so well!”, or “Ah, you got me! I do that too!”, or “Oh, those [star sign]! That’s exactly how they are!”, all of which binds you into a social fabric and identity that rarely exists elsewhere.

And thirdly, through the supposed ‘compatibility’ of different star signs, it gives people a guide to who they should try to form a relationship with. Statistically, by far the number one danger to women is their male romantic partners, both in terms of physical violence but also in terms of the possibility of psychic distress. Will he dump me? Will he cheat on me? Will he leave me to do all the house work? He seems like a good guy now, but is he just tricking me until he thinks I’m stuck with him? Does he secretly listen to Andrew Tate? Will he start doing that a year into our relationship and suddenly completely change? There’s no way to know these things, and under patriarchal capitalism men are under constant social pressure to gain these behaviors and traits. So a system that claims to give even the slightest insight into who you can trust to be a good partner offers a huge psychological comfort.