> if earning another £100k takes more amount of effort it took to earn your first £100k.
That's not the issue. The issue is that the 2nd 100k is worth less in terms of happiness than the first.
Various studies have shown that after around 80,000 peoples happiness is proportional to the amount of money they earn, and after that it levels out.
Thus if one didn't really care too much about that 2nd 100k, making it merely 50k might just be enough for the person to throw up their hands and say "its not worth it, I'll spend the weekends at home instead of at work".
That's not the issue. The issue is that the 2nd 100k is worth less in terms of happiness than the first.
Various studies have shown that after around 80,000 peoples happiness is proportional to the amount of money they earn, and after that it levels out.
Thus if one didn't really care too much about that 2nd 100k, making it merely 50k might just be enough for the person to throw up their hands and say "its not worth it, I'll spend the weekends at home instead of at work".