The same is true with healthcare in America. It's actually not that bad if you have a decent insurance plan and some cash. For high-income earners, which is the people we are talking about leaving from the UK, it's most likely going to be a net gain over time to have the higher salaries and lower taxes.
There's a reason the best engineers are going to want to leave the UK, Canada, India, China, etc, and come to the USA. It's worth it. I personally could work from anywhere including the UK, but why would I subject myself to such lower pay for little or no real gain?
As for me, I gave up on insurance once it got to $800 a month (which was the same as my rent). Denied coverage from then on, claimed religious exemption, and built a house with the money I saved. Paid $4,500 at a local birth center for each of my kid's birth and neither have ever been to a hospital or doctor.
So complaining about "how bad things are" is actually "terrible" on your part.
Status of living is higher for many folks who move to US in terms of ability to actually use the outdoors (less pollution, less population, a civic sense of cleanliness, better traffic and so on), less corruption, better police force, better government, better healthcare (not cheaper), better food (regulations) and so many more angles. Obviously not all of em apply to all countries, but there is a good mix. Not to mention US dollar goes much further in many countries.
There is a reason why US actually rejects 100s of 1000s of H1B applications every year.