As I've said many times back in 2016 and thereabouts, a lot of people at the time were very angry when the BBC and other media were literally every day showing all those people flooding into Europe, and we had many people coming in illegally to the UK via boat or in the back of lorries (thanks to our lack of border protection, that continues today). In 2015 and 2016, it was a big issue for the whole of Europe and Germany and Sweden DID suffer a lot of problems for a while - and the media perhaps appeared too supportive which did nothing more than help start the 'woke' arguments against the press.
Nigel Farage capitalised on this and did the whole 'breaking point' thing. We had people going on about, let's be honest, mostly muslims and the man or woman on the street claiming things like the great replacement theory and other racist stuff (fair enough, there are genuine concerns about some people coming into the UK without proper checks) but NONE OF THIS had anything to do with the EU.
But it became a focal point of the referendum, and people seemed to think if we left the EU then all our problems went away. They forgot about the benefits of freedom of travel, and how many people want to live, work and travel throughout Europe as easily as jumping on a train to go from London to Manchester.
I know someone who was pro Brexit because he was very honest and upfront that it would benefit him, and I'm sure many other people with a lot of money and access to money for investing, who saw the benefits. But the person who voted to get rid of the foreign speaking people in their town? Not so much.
Perhaps the 'best' thing about Brexit was that all these people who wanted rid of immigrants were now able to say they supported Brexit because of meaningless phrases like 'taking back control', 'not being ruled by others' and could hide their real motives. I expect many are now very angry because Brexit is hurting them financially, they've lost the ability to move to Spain, will pay more to go to Europe and queue up and need visas etc, and yet despite all those things there are still boats turning up on the coast... so much anger in fact that they're now attacking the RNLI!
Boris plays a huge part in all this because he didn't have to do Brexit as he did. He continued to show the party fears of losing support to further right parties, despite the actual numbers of people that might vote for extreme parties are likely very small numbers in the grand scheme of things.