TL;DR - Racism at the heart of the rise of the far right; corporations extracting wealth from every economy with no scrutiny, making us all poorer.
Politicians like Trump and Farage prey on people who feel they have been left behind and forgotten. Similar politicians all over Europe, some in power, some in opposition - Germany, France, Italy, Spain, Greece etc.
It's not a new phenomenon, but it's exacerbated and brought to the fore due to social media and globalisation.
Sticking with Trump and Farage - far right politics focus on slogans they feel disillusioned people will attach to, and it's mainly around immigration and race, see they took our jobs, illegal immigrants cost xyz, causing NHS backlogs, they're a danger to society.
It's all horse sh*t to be blunt, and exposes the people who buy into it as fundamentally racist...although they may say "I'm not racist, my son's football coach is Muslim" or some other nonsense to defend their beliefs.
Having one or two acquaintances that aren't white doesn't mean you're not racist.
I believe racism is fundamentally the main reason people buy into these right wing arguments. Brexit was the early days of serious change in Britain, and it's (as expected) turned into a sh*t show that has done nothing but make people poorer, line the pockets of the already rich, make a perfectly working border and import/export system impossible and complex with additional costs, increased the inadequacy of the NHS...the list goes on.
Whether obvious or thinly veiled, there is a sense of old school imperialism in a lot of people in the UK, hence the Brexit vote and what we see now. We ceased being a superpower long ago, the empire thankfully collapsed, but there are still ramifications to this day...and that mentality is still part of a lot of people, most of whom were never around back in those days i.e. before Indian independence in 1947.
Starmer and the Labour party have a mountain to climb because the country has been bled dry by corporations, aided by the Tory's and big money lobbyists. For example, it's an absolute scandal you have to pay some of the highest charges in Europe for water in England and Wales - add to that the fact these companies have only extracted wealth and barely invested in infrastructure - allowed to run amok during the last 15 years of the Tories.
This is happening in other sectors - de-regulation allows companies to extract as much wealth from the economy (our pockets in the end) with very little to show as a final product.
Therein lies the problem - centrist or left of centre politicians find it too difficult to change the status quo given the power behind these corporations = little changes, people are dissollusioned and the cycle continues.