Then you have a single woman living in a 4 bed alone because her children have flown the nest and "why should I leave because it's my home".
Actually very often it's simply because there aren't any 1 beds available for her to downsize to. In some areas downsizers have the highest priority for smaller flats - often above all other need categories. There's something very wrong - a sign of how serious the public health housing emergency is - when vulnerable disabled people are left homeless or in homes wildly unsuitable (eg. mobility issues in a top floor flat), because all the 1 beds have gone to downsizers.
Which leads me to...
As individuals, we also have choices to make, particularly regarding the amount of children we have.
Circumstances change. People get sick, or lose their job in a pandemic, or need to flee domestic abuse. None of those things are planned, nor are they a choice.
The cost of housing is spiralling. Essential workers in London and other high housing crisis areas - nurses, teachers, cleaners, etc - shouldn't have children? They can't all 'just move' because, aside from many needing to be close to family or support networks, expensive areas need essential workers just like everywhere else does.
Also if everybody moved, the cheaper areas would no longer be cheaper... We're had numerous threads on here, with vocal hostility from locals towards members of the 'London exodus'.
There was a council house programme on C4 recently and I couldn't believe there were families who went on to have 5/6 children in a small 2 bed flat.
These TV shows always show the more extreme cases. They actively seek out participants who they feel might fit the stereotypes.