Apparently, there are enough empty homes to house everyone who needs one, at least here in the UK. So it's political will rather than lack of housing, really, as well as the fact that we allow some people to have multiple homes that they may use only a handful of days a year, or as airbnbs or just sitting empty, because property here earns more money than a working human and you can just let it sit and reliably cash in in five years time. They keep threatening there will be a house price crash but it never seems to happen, or if it does, for long. BUT you can't just look at homes, you need to look at the infrastructure as well. Are there enough schools? GPs? Hospitals? Jobs? Food? Clean water? Sewage facilities? All of those things also need to be increased if population does, and they just haven't here and are creaking under the weight. But it's STILL growing. People like to blame immigration but in reality it's 50/50 native population just having loads of kids and people coming from overseas. People from overseas will often work for a period of time and then leave as well. It's a small island with limited resources, at some point we're going to need to ... just STOP.
The mice experiment is so interesting and horrific. I sometimes wonder if we have not already reached that point where it is causing people irreparable harm. You have the hikkomori in Japan and 'shut ins' all over the world. I don't like crowds because of my anxiety and autism and it's just becoming harder and harder to avoid them. An example - I used to do my shopping in the middle of the night so I could have a 'quiet' experience, now more often than not there's a fair few people trudging round who have had the same idea. Some people like to bring their babies and young kids, which completely ruins the idea of it being quiet. Some supermarkets do try to offer 'quiet hours' where they turn the lights down a bit and ask people to STFU, the trouble is they can't legally enforce it and there always seems to be some arsehole who decides they don't want to be quiet. Getting a GP appointment is impossible, waiting lists at hospital have increased and increased etc - and as someone who is chronically ill it's really affecting my quality of life. Lots of people seem to have moved out of London down to the coast and it's increased the waiting times and crowding everywhere. They obviously have somewhere to live, but that's about it. The local services can't handle the increase.
More money could be given to the NHS, they could be managed better, they could trim the 'middle manager' fat and instead hire more frontline workers who actually do the work... you are right that there are all kinds of things that could help. But as I said before, we are a small island, with limited resources, it doesn't matter how well you manage things (although they definitely should be doing it better) at some point it's going to have too many people to be sustainable, the same as the planet. And no one has the will to address it :(