I kinda want to get a doctorate in computers but being a useless grad student during the collapse of society seems like a poor choice

nah man just study what you like, it's not gonna make you any more dead in 8 years

I'm also deeply in debt
- Well on the plus side you're already in debt so you may as well get more degrees

Throughout history collapses generally took a very, very long time. We aren't on the verge of some Day Of Reckoning. Society can survive quite a lot, including the deaths of 20+ percent of its inhabitants.

dating doesn't have to mean having children.

This is a lie perpetuated by Big Horny to get you to commit premarital eye contact. Do NOT fall for it! Remember your oath!
- No, I will never give up premarital eye contact. It's all I've ever got!
This one girl I matched with on tinder years ago messaged me saying how she wanted a farm and lkke 5 kids so I responded with "woah, that's specific"
- BVT MVH RETVRN TV TRADITIVN!

Do it if you like research and know what you're getting into. It's also okay to not get one.

Consider this as well: if you do a PhD program you will usually be paid and get a tuition waiver and if you drop out after the first 2 years you'll usually pick it up a Master's. If you go straight for a Master's you'll usually have to pay tuition and won't get paid. So if you want, you can give it a shot for 2 years and then do an honest retrospective with the option to bail with no regrets.

And I have an old professor who's literally famous and would also write me a red hot rec letter and I also have three undergraduate publications with first authorship on one so like I could probably get into MIT or CMU but also literally why would I do that we should be fighting the fascists not running simulations of obscure algorithms no matter how sexually attracted to the algorithms I am

Honestly, get a math doctorate. It'll actually be useful after the revolution.
And speaking of the revolution, unless you're planning on singlehandedly fighting off the US military and have a realistic plan to do that, maybe don't hinge your entire life plan on hoping that there will somehow magically be a revolution starting tomorrow.
- I don't have the skill or interest for math lol and I'm not expecting a revolution just a general malaise and lack of employment
Learn to hack, learn to quadcopter. Focus on banks or industrial control systems.
My exact feeling but I feel I'd be useless either way, I'm a mediocre autodidact and no hackerman. Only difference is pay, stability and the particularities of my employer. You'll be working for the interests of the same people anyway.

don't spend your own money on advanced degrees, make an employer or the government pay for it

In general, you should never be paying out of pocket for a PhD. Your admission package should cover all tuition plus a (very rough) living stipend. If a PhD program wants to charge you money, it is a scam.
if you're really certain about the timescale (e.g. governments shutdown on 2032 after collapse of supply chains after collapse of Big Oil after collapse of biodiversity), you could strategically max out student loans on the government's dime and spend it all on bunkerization.
- even without the collapse running up loans and then leaving the united states forever isn't the worst plan if you're mentally healthy enough to complete a degree and work the kind of job that hires internationally

do it, trying to plan your life around the end of the world is a fool's errand and will only cause regret

Your degree does not define you. It doesn’t set the boundaries of your knowledge and capacity to learn.

Since you're able to get a good education and you are very interested in the subject, there's no reason whatsoever not to.

It will improve your life and give you much better living conditions no matter what happens, and you can always participate in orgs or go to protests on the side if that's what you're into.

You don't really control where capitalism will lead us and when, but you can control what you do to give yourself better chances since you seem to have the financial ability.

It will improve your life and give you much better living conditions no matter what happens
When it comes to a PhD it might actually hurt OP's chances, since having a PhD usually locks people out of "lower skilled" jobs. If OP is OK with the kind of jobs he can get by getting a PhD, or wants to stay in Academia, all power to him, but he must know some non-PhD jobs might be out of reach afterwards.

i assume that you mostly do this either because the topic interests you or you expect more money if you do this, which are both valid reasons to do stuff. You will probably be dependent on wage labor for the rest of your life and there are no revolutionary jobs if you live in the imperial core

Also, if it's for the money, you could use your additional gains to further your revolutionary interests, e.g., by using your newly gained capacities from having less to worry about economically, to organize