I think I can at least somewhat understand your position, despite still being in my 30s myself, and want to try and help despite my inexperience.

First thing, to answer the question in your post title: I know of people who have, I know many people who are in the addiction/recovery scene, and although I have a very pessimistic outlook on the chances of full/real recover for such issues, I do know at least a couple cases of people turning their lives around in their 40s from such problems. These were people who had a long list of criminal charges, absolutely no money, homeless/living on friends/families couches, very deep-rooted trauma and mental health issues, no healthy relationships, etc. People coming off of decades of heroin or alcohol abuse have to start at just about the lowest point possible. A small percent of people in that situation recover(as in getting and staying clean), and an even smaller percent are truly "healed" - to the point where they can prosper and gain inner wellbeing and actually prosper in life, but it does happen.

Even if it's only 2 or 3% of people in such circumstances, I don't think the outlook is as bleak as the numbers make it seem. That just means you have to be in the top couple % of people in how hard you work towards getting better, if you know the numbers then you know your goal - you have to do whatever those top 2-3% do, and then you will accomplish what they accomplished. In your situation, I'm sure the numbers are much better, as you actually have some money, some education and career experience, presumably less deep-rooted trauma and mental health issues, no criminal charges, a place to live, and maybe even some healthy friendships or family relationships (though I'm sure you have some unique problems of your own that complicate things, hopefully it's no so bad to outweigh all those other cons). I say all that to hopefully give you some hope, and also to give you some perspective that'll help you figure out what path you have to take to achieve the results you want.

Another bit of information that might give you some hope, is a quote from renowned psychologist Carl Jung, who famously said "Life begins at 40." He also talked a lot about "mid life" and how it often leads to a mental/spiritual crisis and results in deep depressions and/or intense anxiety. In his view this was part of the transition into the "second half" of life, and overcoming this crisis was a natural part of psychological maturity. I definitely don't have room to go into all of this here, but if you want to look into Jung's work I think it could really help you navigate this state your in(even if this mid-life transition isn't the primary cause, his work of course goes well beyond that and has helped so many people, including myself, recover from a state of suicidal ideation and meaningless existence)

The fact that you mentioned suicidal thoughts makes it clear that the problem is psychological at root - material circumstances can definitely make things worse, but people in a healthy psychological state can bear much more extreme troubles while maintaining a love for life. "A man with a 'why' can endure any 'what'" as another renowned psychologist, and holocaust survivor, Viktor Frankl said (I'd also recommend his book, "Mans search for meaning" - ESPECIALLY for someone who considers themselves a NEET). That being said, I think a professional psychologist is indispensable in your situation, even though suicidal people are often the least motivated to seek one out, you have to find a way to make yourself do it anyway, and believe me I know how hard that is in some cases. It doesn't help that finding a good therapist is extremely hard, and extremely crucial, as there are so many practicing therapists out there who either won't click with your or are just plainly not competent enough to help others with serious troubles.

I have a lot of my own ideas, and have studied a lot of psychology from different schools, but I'm in no way a psychologist or a therapist so I don't want to impose my views without a disclaimer. Jung says that people who overcome their own issues, which always seem like the most difficult issues imaginable to the person in question, they come out the other side with an inflated sense of the capabilities and a desire to help others, with the sometimes incorrect assumption that what worked for them will work for others. Personal issues always require a very personal solution, but if you wanted to discuss more I could at least give any advice I have on how to find your own personal solution. I know it may be harder for you than it was for me, as I went through all this at around 28-30 years old and I still had the view that I had plenty of life ahead of me if I did manage to get better, but other than that I think I can relate to what you said in many ways.

Reply to my comment if you want to talk more. And if you have anything specific you want to say feel free to - if not I'd be happy to just spew out a ton of information about my own experience, how it relates to yours, what helped me, and what I think you can expect in the process of getting better and the many ups and downs you'll likely experience on the way; knowing in advance what to expect can help a lot as you'll know what setbacks are coming and when you face them you'll be armed with the knowledge that such setbacks are inevitable and you are that much closer to your next victory, and therefore to your final victory, it can also help to know roughly which rung you are on on the "ladder" towards recovering so that, even if it's still a long and daunting climb ahead of you, you'll be motivated to keep going by the realization that you are one rung higher than you were last week and next week you'll be one rung closer.