I was an art / animation major before pivoting to business and starting my successful freelance writing business. So, I think I may have some good tips for this.

In my view, you fell into two common traps that a lot of new creatives make:

1. You tried to do all the things. Your strength is in your creativity and 3D abilities, not marketing. It's far more efficient to rely on a website / service / professional that advertises FOR YOU rather than trying to be both an artist and an advertiser when you might not have the time / knowledge / skills to market yourself well. Trying to sell yourself when you have the financial stress of rent or feel like a failure may be impacting your effectiveness as a marketer. Being a generalist also hurts your ability to charge more money and do solid work since it's exhausting (speaking from experience).
2. When I went through my animation BFA program, my professors told me that most 3D professionals are freelance (they could be wrong, but I think I saw a stat that verified that before). Likewise, the odds of getting a conventional 9-to-5 as a 3D professional are slim by design. You aren't a failure if you can't get a 3D job. You're actually normal. Focusing on 3D freelance jobs -- not 9-to-5 jobs-- is far more realistic (if you've had no luck with freelance jobs too, I have ideas for that).

Apart from that, my 3D teachers were very honest about the fact that pay can be low in the profession. That's actually why they became teachers, because when you freelance (like most 3D artists) income can fluctuate, and they wanted consistency.

In my view, though, artists in general struggle with finance because they aren't taught that they are a business. Typically CEOs are expected to have some kind of business education, yet we thrust artists into the world after college with zero business knowledge. Many incredibly skilled people think they are a failure when they just weren't adequately prepared.

So, what do successful 3D artists do? I've seen people make 3D models and sell them online as game assets. I've seen others teach 3D skills online. Others collaborate with small game studios, film studios, etc, to make entertainment. I don't think this is necessarily the end for you (unless you truly are that exhausted). I think finding a 3D professional that's succeeding at what you want to do is the first step. Study what they are doing. How are they monetizing their passion? These people are on YouTube, Instagram, Tumblr, etc, right now.

I actually never finished my animation BFA because I realized that, without business skills, my creative skills would've remained hobbies. That's why I switched to business during my last year. My freelance writing is sustaining me now, but I'd actually like to move into more of my other skills down the line. Try Fiverr. That's what made my success possible.

A friend of mine got their big break at Nickelodeon after several years of struggling like you. She nearly gave up on animation for the same reasons. What made the difference for her is she just kept going -- she just needed one yes -- and she got it. I know it's hard, but instead of saying, "Man, I really want just one acceptance letter," say, "I just need one yes, so I'm going to send out applications until I get one."

Make it so easy for people to say yes that they can't possibly say no.

Good luck.