I'm not going down the 'no loss to society' route - every death is a loss to society, or should be ...
... but (you sort of heard the but coming, didn't you?) there has to be an element of personal responsibility in anyone's life - you can't just keep abdicating that responsibility to someone/anyone else.
When I had some very nasty mental health issues in my late 20s, I eventually recognised that (much as lots of other people were trying to help) the only person who could turn my life back round was me. Nothing (and nobody) else could do it for me. I eventually crawled out of the pit and am never going back, ever, at all.
Which seems to be the nub of the disagreements above - and, whatever sympathies I have for someone with a real trainwreck of a life, in the last analysis he has to take the responsibility for his actions and their horrible outcome.
Only he chose to start the situation, the people who (with almost insane bravery) tackled a gun wielding robber didn't ask for that to happen in their normal day at the bookies.
Only he must bear the blame for his regrettable death. No-one else at all - not the innocent members of the public who defeated his planned armed robbery, not the 'services' who he engaged with over the years, no-one at all - just him.
Telling people who say that he was the agent of his own misfortune that they are "part of the problem" is insulting, specious and unpleasant - I had expected better of someone who I have always respected for his sane, humane and life-affirming stance on many other issues.
Dave