You could be describing my child just a short while ago, including the nocturnal behaviour, weed smoking, virtually non existent education, no friends, aggressive behaviour, self harming, cooking and eating at night, apparently incapable of applying themselves to anything, just wanted to spend their every waking moment doing what they wanted to do and took no responsibility for anything.
In my case, my child felt like I was always getting on their case so they shut down and I was worried sick about their future.
It made for a tense relationship.
Ultimately, they felt I was not on their side, and I suppose I wasn't, because I felt I knew what was good for them. I still believe that, however, this is what I have learnt and I hope some of it will be helpful for you OP.
I decided that for a space of 3 months, I was going to treat DC like they knew what was best for them, even if that meant in my mind I didn't agree. I put my trust back into them to make the right choices for themselves, whatever they may be.
I also decided that I would focus on what was best for me during that time.
When DC went to buy weed, I saved the lecture and told them that was fine so long as they didn't stink the house out with it.
When DC chose not to engage with education, I chose to trust that they knew what was best for them, mainly because I knew that no matter what I said, they weren't going to pay attention anyway.
I still suggested opportunities, but if they refused, I respected their choice without showing I was frustrated with them, easier said than done.
Within days, DC was opening up to me in conversation and I may not have agreed with much of what they liked/wanted/did/thought but I accepted that they were entitled to their own choices and just as they weren't trying to persuade me to like/want/do/think the same, I gave them the same grace. I made it clear that they were in charge of their own choices and so long as their choices didn't affect me, that was their right. I knew I could not make DC see what I considered sense, and tbf they weren't asking for my advice, so I drastically reduced the guidance and advice, trusting that this is their path in life.
Yes, it was beyond frustrating that they appeared to me to be making poor choices, but that was their choices to make!
I discovered that DC saw it as I was perpetually disappointed in them, that nothing they ever did was good enough for me and that I simply wanted to 'control' them, whereas I felt I was just doing what was best for them.
DC didn't look any further than the end of the week, whereas I was looking much further into the future and their choices in the present had me extremely worried about their future.
I gave them control over their own life and choices without any pressure.
I found a council run youth club and offered to take DC there and they agreed.
They made some friends and that was the start of them finding something outside of the house that they found enjoyable.
Within those 3 months, when I refrained from sharing my worries for their future and endlessly trying to make them see sense, and simply accepted their choices, they began talking to me, telling me of their decisions. They began showering regularly, wanted to spend more time in my company, talking to me more, and through this, I was able to reflect their decisions back to them by asking them what they would like to do instead.
At first, they said they wanted to sleep all day, and when they received no pressure from me, just an acceptance, they felt accepted and slowly, within a couple of weeks began to realise they wanted more out of life.
I realised it had to come from them. They had to believe I accepted them for who they were and that included what they wanted to spend their time doing.
My only stipulation was that it didn't affect me or my home.
My concerns were well founded at the time, but they were my concerns. DC didn't share my concerns so I trusted them to do what they felt was best for them.
After a couple of weeks, DC began confiding in me and I realised that 99% of their issues came from feeling they weren't accepted, that they weren't trusted to make good choices for themselves and that they were only loved conditionally, so long as they did what I wanted, they would be loved, so they rejected my concerns, feeling I was just trying to control them, that I was angry with them a lot of the time.
Yes, I was frustrated, but that was MY frustration and I tried hard not to put that on DC.
They didn't make choices I agreed with but they didn't affect me so I stood back and gave them that right, to make choices for themselves.
Once I adopted these ways of dealing with DC, they began to feel that I understood them more, and they realised they weren't happy the way their life was.
I realised DC had been incredibly unhappy and their behaviour was their way of expressing their deep sadness.
Once they felt accepted, they got happier and more relaxed and then they began making better choices, because they felt they were worth better.
I tried guiding DC for years and years and all it did was destroyed their trust in me.
When I chose to trust them, even when it didn't make sense to me, it paid dividends.
DC is now much happier, making better choices, and has better self esteem now, because they know that no matter what they choose to do, I love them and accept them exactly as they are right now.
Who knows what the future holds?
What I do know is that all of the should have/would have/could have talks never helped one bit.
I spent years and years hoping they would listen and take my advice, and it never worked. What it did achieve was to make sure that DC turned to people who did accept them, they would spend many hours seeking to find people to talk to online who didn't try to guide them. By doing this, I gave any influence I may have had over to complete strangers who were now influencing them and their choices over the internet.
Now I trust them to know what's right for them and they are making progress, they spend less time online, more time in the real world and they talk to ME about their life, not strangers on the Internet.
Ultimately, if my DC messes their life up, it is their life.
I have made mistakes in my life and when I have, if anyone had come down on me hard, telling me what I needed to do, or saying something like 'Well what did you expect? You need to do XYZ and sort it out.' I would automatically feel pissed off and distance myself from that person, despite their best intentions for me. My child is the same.
So I approach it from the angle I'd like to receive it from.
Hope some of this is helpful.