Like my friend’s controlling abusive violent ex who went on the sick 15 years ago when she left him to avoid paying child support and also so he could monitor his new girlfriend 24/7. No one knows what “wrong” with this guy and he is very vague when asked.
I wonder who'd want to employ someone who's known to be violent? Then again seems like lots of violent and abusive people are in employment and a cruel irony is often it's their victims who end up on benefits (as a direct result of the abuse). There's lots of threads from women on MN who've been or are in that position. Many have to give up their jobs to go to refuges, and also because of the effects of the abuse on their health and or because of men like your friend's ex who avoid paying child support (including higher earners).
You're right about the consequences of wage suppression and the insufficient amount of social housing. That's massively increased the benefits cost.
Those two issues are because of a false economy approach, which also includes funding cuts to public services. For example, lots of people on long NHS wait lists so their health deteriorates by the time they're seen. Punitive benefits system is another issue. Stress affects health, and so does poverty.
The other problem though is there aren't actually enough jobs. There's more people on jobseeker benefits than total job vacancies. (That's not including people on sickness benefits).
It won't solve everything but scrapping the false economy approach would help cut benefits costs (and also reduce demand on other public services).
Good and well-funded public services, social housing, supportive benefits system, better enforcement of child support, and work, education, and training opportunities. Costs at first but worth it later on as it saves in the long-term.