As an absolute bare minimum for a poor student I would say 8 gigs is ok and will get you through so long as you’re careful. 16 gives a lot more breathing space and should allow you to do whatever you like so long as youre not being stupid. 32 will be plenty of headroom and last the computer its life unless you’re simulating the entire north atlantic flooding through a major city, then to bump it to its limit.
Or maybe a realworld example, until last month I had a 12 gig machine, I only ever ran out of memory twice whilst working. Once when the project was simply too complicated and once when I was trying to make the software crash on purpose. I do everything from architectural interiors, product visuals, animated 4k theatre set backdrops. Cinema 4D after effects, photoshop etc. I don’t do fluid water, smoke or fire sims, I don’t have the patience. I’ve had to close email, itunes and my web browsers a couple of times but it has all been manageable.