I think because they/we started living in London when it use to be better and now can't be bothered to move, can't afford to move or are stuck in their rut.
London used to be great.
It was never cheap but it had great restaurants, gread arts and entertainment and theatre, lots of choice for workers at lunchtime (no stale sandwichs - sushi, mexican takeaway, hummus bros, abocado, starbucks and prets, salad bars), easy to get around on the tube and by taxi and no congestion charge or ULEZ There were a lot of pluses.
Now honestly it's a shit hole.
The cost of everything is astronomic because it was always more expensive due to overpopulation = land shortage = high rent. But now add into that energy costs and inflation.
The tube is now really expensive, horrible and dirty and personally I hate it now in a way I didnt' feel so antagonistic towards it before because of Covid and I can't bear the overcrowding. It was never nice but now I feel repelled by overcrowding in the rush hour which I didn't befire.
You can't get around anywhere by taxi or car because all the roads are blocked off with these stupid Low Traffic Neighbourhoods (LTNs) so all cars are funneled onto a few roads where you sit in idling traffic forever. LTNs, not to mention congestion charging and ULEZ and parking make andy even a quick trip to a supermarket where you want a car to pack a family shop hell on earth.
All the nice lunch places have closed down in the pandemic because there was no trade as everyone started working from home.
Because it's so expensive and hard to get around it's harder to get to enjoy the stuff that used to be fun about London.
I'm still here but honestly I hate it. It's not what it was at all. It's very sad. A big part of it is down to insane traffic policy that affects everyone whether you are an Uber, taxi or car user or not - because it reduces population movement which reduces economic spend which affects prices and causes stuff to close down. It's not just Sadiq Khan alone but he's got a lot to answer for here IMO.