I feel like the UK is in some kind of cultural decline for a while now. I know as every generation gets older things 'were better in my day' but looking past that, I think some of the points made above are very true. Especially from those who have had perspective of living in other countries. I can relate to the sentiment from Vietnam - when I visited Ho Chi Minh city the vibe was amazing, even if there wasn't the outright wealth of Europe, there was community, growth and you could see the living standards were improving. An exciting place to be. If the opportunity came up, or even if I have to find it, I would seriously consider moving somewhere else. That said, there are some benefits of the UK such as healthcare, most people have a decent standard of living with regards to material possessions, education isn't terrible and there are still opportunities out there if you like mindless office jobs. However I think the community, hope and positivity that we had whilst I was growing up have definitely been lost. There are some pockets left. I lived in Bristol for a while and there was a thriving community there, in fact many, and most people were sociable. Back towards London you're lucky if anyone talks to you on the street and if you talk to them you're the weirdo.
I'm not sure what it is about the UK but I've felt for a while that there is a huge sense of undue entitlement across much of the population, maybe even unconscious or societal. I feel like an injection of reality and humility would help, but we'll never get it since our politics has become driven by populists. Unpopular or even just difficult ideas, however beneficial, are overlooked.