You know what happens to people who work all hours, get pushed beyond limits, work into the night, sacrifice their own time and their families ? One day they walk into work and are greeted with keys and laptop please, you're redundant, thanks now fuck off.
I think a reasonable amount of this work:life balance relies on the reward. I know people who work really long hours and don't really get much benefit from it.
I've worked very long hours, for no initial extra pay, at times in my career. However, down the line it's led to promotions, significant bonuses etc..The amount of money that, over a period of time, does change your lifestyle and your families lifestyle.
It's also your personal limits and desires. I'm ambitious but also driven to do the best job possible. I'm not driven by money particularly but I'm in a position where I can probably retire reasonably comfortably by 55 at the latest. Retiring early is one of the benefits of 'having more toys'.
My work:life balance is grounded with a few rules a) I make sure that I'm around in the week to take kids to football, swimming etc.. after their school day. I don't want my work to impact their ability to do hobbies, and b) I make sure I don't work on weekends (unless extreme circumstances).
I do work long hours though. I might start work at 7am. I might finish at 10pm. But I do on most days, have a 2h gap between 5 and 7pm to take kids to sports club and have a family meal together. I probably work high 40's to low 50h weeks regularly (but get paid or 37h). It means I have long working weeks with limited free time but I do get the weekends with the kids and my Wife to do as we please. I also get to be ambitious in my career.
The above wouldn't work for others. Their job/profession may not allow for the flexibility I have. I'm conscious that most jobs aren't necessarily giving bonuses or promotions that can make a big difference financially. I know some people wouldn't want to sacrifice their evenings virtually every week night.
What is right for one person won't be right for another person. It's down to us all individually to find that right balance for each part of their life.