I've spent a bit of time now and again as an involuntary patient and it is the worst, dehumanising experience. I can't imagine how angry I'd be after 3 years of it.
One thing that I have learned about involuntary orders is, regardless of how I'm feeling, and how strongly I might feel, something I'm doing isn't right. It can often feel punitive, but that is just a feeling - no one else is actually benefitting from your situation.
So, it's clear I'm doing, thinking or saying (or all of the above) something that's wrong. Something that's ticking the box on their Involuntary form. The only way out is to change that. Literally.
Sometimes it's obvious (like, I need to stop planning my suicide), and sometimes it's not. After 3 years, it's time to approach this with a clean slate. Even if you've tried it before, your freedom is at stake, so keep trying. Talk to them. What am I doing/not doing? How can we change that? How can I do better? Can we come up with a plan together for getting me out of here? (Plans are good - doctors love to see patients following a plan). Know in advance that they're gonna say things you don't like and don't agree with, but turn that anger into constructive motivation.
Your anger makes perfect sense. It really does. But yeah, it's contributing to your stay rather than shortening it. No matter how angry these people make you (especially after 3 years), you have to let that go. Your freedom depends on you being able to work with your treatment team, not against them.
That doesn't mean stop fighting. Just fight smart. You can do this. They will help you if you show them you can bring it...