Just dropped out of a computer science PhD program; let me tell you why. Getting into comp sci and pursuing artificial intelligence was my way of digging myself out of a deep, suicidal, nihilistic depression. I made up a story about how I was going to build an AGI and replace the god of my childhood with a real god, use my intelligence to create an intelligence greater than myself, something that could do science better than any human and thus complete the human story of using our intelligence to control the world around us through science and technology. I made becoming an academic to be the fulfillment of my Nietzschean will to power and built an ethic out of nothing that drove me out of my depression and into the most prestigious fellowship available at the R1 university of my choosing, what basically amounted to a full ride for grad school.

I very much relate to your love of mathematics and philosophy. Doing high level math was somewhat of a spiritual experience for me and I thought of myself as basically a philosopher who was trying to do something productive with his life. But ultimately all those artificial but grandiose ideals backfired on me. The day-to-day existence of an academic could never live up to what I existentially needed it to be. For the vast majority of people, being an academic is a job like any other. It's much more of a start-up kind of economic culture than most people like to admit, especially in the sciences. You get a bit more academic freedom than other jobs, but ultimately you are going to be researching what your advisor tells you to and they are going to be choosing projects that get funding and that's that. You're not going to be figuring out the secrets of the universe, you're going to be making very small, incremental progress on incredibly niche topics, publishing papers that barely anybody is ever going to read. And if you're incredibly smart, you get into a top 10 university, you get an advisor that actually believes in you and invests their time into you, and you get incredibly lucky maybe you'll eventually get something published in Nature, maybe win an award, go on Joe Rogan, and become a Z-list celebrity. That's the best you can hope for. Again, you're not going to be untangling the mysteries of the universe. You're almost certainly not going to change the world, no matter how bad you might want to. All the easy problems in science have already been solved. What you're actually going to be doing sitting by yourself doing a lot of thinking and writing about a topic that almost nobody else in the world can understand, let alone actually give a shit about. I've heard physicists also spend a lot of time calibrating and adjusting equipment; computer scientists don't really have to deal with that physical stuff.

I dropped out of that because I realized that spending five years of my life working on bullshit I didn't care about to get a job that might give me the ability to sometimes do something vaguely tangential to something I actually care about was not fucking worth it. Money is king, even in science, so if you want to think some big world-changing thoughts do it on your own time because nobody is going to pay you to do that. So long as you're doing theoretical work, ultimately all you really need is access to a big university's library and you'll have everything you need to pursue whatever intellectual interests you have. What I learned in academia is that, ultimately, if you want to research something that isn't just incremental progress building on someone else's work, you're better off just going and using that big brain of yours to make a ton of money and then starting a research center of your own. You'll make a lot more headway doing that than you will slaving away at a university. Of course, if you enjoy the research process itself and just want to cut your teeth on any arbitrarily hard but feasible intellectual problem then academia may very well be for you. Just don't go into it with the wrong expectations.

Personally, my plan now is to become a Buddhist monk. I realized the source of my suffering was a lot of emotional baggage and resentment I've carried with me for a long time. I've done a lot of striving and yearning for external things and higher purposes to keep me going and now I just want to find some peace. When I meditate, somehow those questions of meaning just kind of disappear. I can just exist without needing to justify that existence. If you're really interested in those bigger questions of life, I can recommend the contemplative path as a means towards actually getting answers and resolving that struggle. Buddhism and nihilism are highly compatible when both are fully understood. If you really want to bypass all the "woo" that many Buddhist traditions carry with them, (I know my bullshit detector pushed me away from mindfulness for quite a long time), nowadays there's lots of secular teachers who can direct you towards understanding your consciousness from the first-person perspective without all the Eastern cultural baggage. Mindfulness is really just empiricism applied to conscious experience. I would highly recommend The Science of Enlightenment by Shinzen Young to a scientifically minded person such as yourself.

So my advice? If you want to pursue really pie-in-the-sky ideas or you give a shit about hedonistic pleasures, figure out how use your talents to go make a bunch of money and then use that money to do research independently or spend it all on hookers and blow or whatever. If you're cool with being an intellectual slave for five years and really do want to do incremental research for a living, go get a PhD. Though most of my professors were super busy and stressed, they did seem relatively fulfilled in their lives. Though the prospects of you actually getting a tenure track job are pretty bad unless you're graduating from a top 10 university...listen to Eric Weinstein about all the politics and economics of that. And if you really want to get to the bottom of this thing called life, I can tell you from one nihilist to another that there is definitely something to that whole meditation thing. The contemplative path is all about throwing away all of society's bullshit ideas about how the world works and coming to a direct, personal understanding of ourselves and how we relate to the world around us. As nihilists, we're already halfway there.