He needs to lose the attitude that he's owed a second chance at life. And accept that nobody owes him anything. He's wanting the moon on a stick and complaining when he doesn't get it. We all get one life, there's no "dress rehearsal" and it doesn't come with pre programmed second chances. His anger doesn't come from [insert all the excuses you've made for him here] it comes from him not accepting this fundamental fact of life and his sense of entitlement that he thinks he should have more. He has fucked up and now he's going to have to work twice as hard to fix it. Which may involve starting at the bottom and/or doing things he doesn't want to do.
You quoted my previous post a few times asking what I think he should he do. I told you, if you bothered to read it properly - Accept his situation and where he's at. Look for more jobs with more hours in hospitality, study around those job(s) for qualifications in hospitality, turn it into a career if he wants. But suck it up and accept that hospitality is where he's at for now.
People wanting to change careers, which is what he's trying to do at this stage if he wants out of hospitality, have to be prepared to go back to studying and live like a pauper with no social life (because they'll be working in whatever job they can get (McDonald's is always popular with students) when they're not studying).
He needs to accept that he's made himself almost unemployable for the jobs he wants. Why would an employer pay him whatever the NMW is for a 20yr old who's messed up, when they could employ a 16yr old with no issues on a cheaper NMW to do the exact same job? This is the reality of his situation. They're not going to pick him.
He needs to look at the options open to him and stop dismissing them as beneath him.
He could take a level one qualification at college this year and that starts getting his toe in the door for something or other.
He could join the armed forces.
He could embrace hospitality and make that his career.
He could stop pissing about with Indeed and apply to actual companies for actual jobs, with a tailored application for each.
He could walk into an employment agency, discuss his current skills with them, do any assessments they demand of him and see what temp work they could get him alongside his current hospitality job (and he needs to say Yes to anything offered, because he needs to get onto their good side and prove he has a good work ethic, not be a picky PITA about not wanting this job or that job because guess what? That attitude leads to them not calling unless they're desperate and offering majority of the jobs to other people first who they know are more likely to say Yes).
He could apply for seasonal work, they often have quotas for permanent positions which they'll fill from the seasonal workers, so he should make it known to management that he's looking for a permanent job not just money for Christmas.
If he applies for a picker/packer warehouse job he needs to apply as someone wanting a permanent job, not with a view to getting an apprenticeship elsewhere one day or going to college in a year, of course they're not going to want to bother training someone who they know will leave!
He has options. It's no good looking at them and dismissing them all just because they involve going back to scratch for him or won't lead to this illustrious career he thinks he's cut out for.
He needs to forget about all this wanting a good job so he can keep pace with his old mates. That ship has sailed. They didn't fuck up their lives or suffer health issues, they made consistent progress and are now years ahead of him. They're going on holiday without him, they're making jokes about his cheap clothes, he can't afford to socialise with them and he's working when they're off work. It's over, he's a joke to them, he needs to let it go and move on, make new friends. Stop thinking (working class?) people are beneath him and he's going to fall in with a bad crowd. That's choice! Nobody has to fall in with a bad crowd. If the nice people don't want to be friends with him it'll be because of his attitude problem, thinking he's superior, his propensity for blaming others when life doesn't go his way and his aggression. Which is something he can fix (with therapy).
If he wants it badly enough and if he works hard enough and if his health allows (biggie, that one, not everyone's does), then maybe he'll have a good career job one day. His old friends will still have moved on though by the time he arrives in that place. I'm not saying he'll never see them again, but his and their lives have already gone in different directions and their previous closeness has been lost, that isn't something that can necessarily be reversed or that he can "catch up" with.