Well, I was none the wiser because i hadn't bothered to check this person's background as it seemed like an innocent question. And to be fair, I think the negativity didn't start with the OP (if you look at this like an objective observer) I also think the question is interesting and valid to people who might come on this board and be wondering the same thing. That's why I still post on here even though I'm not living in the UK anymore. I WISHED i had someone to give me more advice when I was struggling or even to commiserate with and some people on this board definitely helped me so much so some I still keep in touch with. It helped to know it wasn't just me going through the same thing.
As for the OP's actual question, one thing that wasn't really brought up on here was how the country's culture might change because of Brexit for Americans. In my own experience, being part of the EU was the biggest thing that saved my experience there. 99 percent of my friends were from the EU. So I'd be very lonely indeed without it. Also, especially with what's going on now in the US. I so wished the US had something like the EU to safeguard with human rights etc, like maternity leave, etc. That was a big draw for me in moving to London. Now, those rights might stay but it's something to think about and definitely something to be concerned about.
Some people do move to the UK with access to Europe being a huge draw, not just to visit but the laws that protect people and the chance to meet so many different kinds of people. So without that, yeah, I'd say the cost benefit isn't exactly the same anymore if those things were a big draw for you.