There has been a series of unfortunate events beyond our control (Covid, Russian war etc) however, had the country been properly managed after the financial crisis things would be nowhere near as dire as they are now. At that point in time the Government could borrow at negative interest rates over a very long period. A huge investment in infrastructure, skills, energy and food security and developing key growth sectors in technology, medicine etc should have been implemented at that point rather than austerity. This would have led to growth and rising living standards instead of a decade of stagnation so that we went into this period of turbulence since 2019 in a very weak position. Then we have a Government so utterly incapable of understanding basic economics that they thought a solution to our economic problems would be to trash our international trading relationship despite us having a huge balance of payments deficit already. It was blatantly obvious that Brexit would permanently damage the economy and make everyone poorer. While there have always been economic peaks and troughs it is unprecedented to have 15 years of zero real-terms salary growth. And with further geopolitical instability to come, natural resources dwindling and eight of the ten largest cities on Earth being in coastal areas that will be underwater in a few decades due to climate change, we've seen nothing yet in terms of mass migration. Not a situation in which it's a good idea to be reliant on importa for basics like food and energy...
The generation now in their 30s and 40s have been royally screwed with the highest childcare costs of any developed country, huge housing costs, student debt, no salary growth throughout their careers, inflation, Brexit, a terrible education system for their children, and now massive hikes in interest rates while they fund early retirement for those whose generation bled the state dry, sold off everything of value, let infrastructure crumble and created this mess, but repeatedly chant how they "have earned" the pensions and benefits that they paid nowhere near sufficient tax to fund.
Part of the problem is an extremely badly educated electorate who seem unable to understand basic economics or that the social contract includes responsibilities as well as rights. People do not demand change and are happy to tolerate this ongoing mismanagement, even actively vote for it. Refuse to look at data and assert that opinions based on fantasy are of equal value to those based on data and facts. There is truth in the saying that a country gets the Government it deserves. While this would always have been a relatively difficult period due to external events, the majority of the UK's problems were entirely foreseeable and avoidable.
I agree with @TheNoonBell that most of the west is in a state of managed decline and sadly this will only get worse with living standards continuing to fall sharply over the coming decades. Gross mismanagement in the UK has hastened the process: counterproductive domestic economic policies, absurd foreign/ trade policies, an economically damaging tax and benefits system that politicians know is damaging but refuse to change, no investment in the key areas required to improve things, plus a refusal to reform areas like healthcare and eye-watering unfunded pension liabilities that are not even included in the national accounts that are quite obviously unsustainable. It is a mathematical certainty that these things will HAVE to be changed because the country literally cannot pay them, but they'll wait until collapse until they do so, causing far more damage. And a chancellor so inept that he has arranged around 1/4 of recent Government borrowing on an index-linked basis so the one benefit of the recent high inflation (reducing the real-terms value of our debt) was not available! You really couldn't make it up. Everything designed around "optics" rather than what will actually work.
Head in the sand, ostrich syndrome and no evidence-based policy making whatsoever. A refusal to do what needs to be done even when it is staring them in the face and an electorate just as irresponsible as the politicians whose answer to everything is "somebody else should pay for it".