I'm unhappy and have been unhappy for years.

It sounds like you want to be happy, so you made this post. That's a good step.

Pressure landed me in a field I have absolutely no interest in.

You did <a>, <b>, and <c> to get where you are now, <d>. There's nothing you can do about <a>, <b>, or <c>, so forget about them. There's a lot you can do about <d>, and it sounds like you want to. Good.

I'm far into further education, have many more years to go and will be in tons of debt soon.

You can change course at any time, regardless of how you got here. That may (or may not) be the right thing to do.

Dreams of being a hacker, working in the valley at a young age with relatively few responsibilities are quickly vanishing.

I don't know a nice way to say this, so I'll just say it: So what? I have been a hacker for many years and have never worked in the valley. Most great hackers I've ever known have never been there either. And you'd be surprised how old they were when they really got into it (a lot older than anyone who follows popular opinion would believe). There are many paths to happiness in hacking and there's no age limit, believe me. Forget about what has happened to get you to this point and focus on where you are and where you want to be from there. If you look back, you'll find a way to be miserable. If you look ahead (and do something about it), you may be surprised how attainable the wonderful life you want still is.

I see Facebook pages of high school friends who are living the life I wished to live.

Never compare yourself to others. Ever. There will alway be someone "better" and someone "worse". Know what it means? Nothing. So don't waste one more nanosecond of brain time thinking about it. OK?

Regret settles in, optimism is brushed aside by reality, and I realize there's really no feasible way out.

You believe, not realize, that there's no feasible way out. There's a huge difference between belief and realization. You're confusing the two and must stop doing that. You need to find a way to believe these's a feasible way out. Once you make that leap, all things will once again become possible. I don't know what it will take for you to get that belief, that's a task at hand for you to complete. Find help with that task if you need it.

I've sought to find the "brighter" side of this, but there really isn't one.

Then maybe it's time to stop "seeking brightness" and start putting together an actionable plan to get where you want to be. Again, I don't know what that plan would be in your case, but resources are available all over to help you get started.

I'm deep in a hole, absolutely unhappy with the path I'm on, and jumping ship would put me in a worse situation.

"Changing Course" != "Jumping Ship". Again, it may (or may not) be best for you. Don't decide prematurely whether or not a changing course is wrong.

What's frightening is that suicide has been a thought I've always jokingly entertained, but as time goes on, I find myself lending the idea more validity. I don't know what to do.

Speaking up, even with a throwaway account, was a good first step. It proves how much you really care about yourself. Listen to some of the advice here and take advantage of other resources at your disposable. You are not alone. And you certain not the first (by a long shot) to be going through this. Keep speaking up until you find the help you need. If you want to talk me email me. See my profile.

Thanks for speaking up. Keep at it. And best wishes. We really do care.