London is full of young people who are basically just breaking even, spending 50% or more of their monthly income on rent. I think people tell themselves this is ok as long as they're gaining experience and moving up the ladder.
The fact that people aren't moving away in greater number says more about the stagnant UK economy outside of London, than anything else.
I think we're on the cusp of a massive re-think of how we live and work in cities. This will either come through regulation (rent controls, bans on 2nd homes, tax on unoccupied buildings, etc), or innovation (maybe we'll all have homes outside cities and come and stay in Tokyo-style capsule hotels during the working week).
Right now, millions of people are working hard every day to make a relatively small number of landlords richer and richer. It's unsustainable, and I think some major societal change is coming.