A huge issue is our tax system vs benefits.
54% of people now live in households that take more out from the system than they pay in. This includes the cost of schooling for each child, benefits, pensions, NHS etc... This was only around 42% in before 2000.
There has also been a huge increase in the number of people claiming disability benefits and not being able to work since COVID.
We have become "poorer" because more people are wanting to take but are not willing to contribute.
Go back 40 years where benefits were a helping hand until you got back on your feet, not a lifestyle.
It has become too easy to make benefits a lifestyle choice and too difficult to get back into work when you can "earn" the same not working.
I got laughed at by a SAHM for going back to work when I had twins. I earned £20 a week after childcare and petrol. I would have received more in benefits to stay at home, but I liked my job and didn't want to lose it.
There is also a change in mentality over the difference between WANT and NEED. Being able to take out credit and loans to buy things that people really can't afford, when they could get a second hand version for free.
I know someone who NEEDED a new sofa and took out a £2500 loan with DFS which they could barely afford to pay back, when in reality I they could have got a decent sofa for £200 on Facebook which I offered to pick up for them.
It is many changes that have led to the country becoming "poor".