I don't know what pay packages are like in London nowadays. Five years ago or so my understanding was ~40-60K starting.
When an apartment anywhere costs 300K+ it doesn't seem as good a deal any more. It feels like the junior investment banker of the 1990s could have been considered to be on a path to persistent wealth, whereas now it's a fair bit more ephemeral.
Working 100 hour weeks, after the initial excitement dies down, might ultimately only really be justifiable as a path to great riches or early retirement, not an upper middle class existence.
Would I work 100 hours a week for ten times the amount I'd expect at 10 hours? No, you'd have to give me FU money for that, because the idea there is that I work until I'm burned out and then retire.