Until the more productive and engaged fellows start questioning what exactly are they working overtime for or simply burn out, then they're replaced by fresher more productive fellows and the cycle continues. Best way to break it is to have balance from the beginning, not after you burn out a few times and form the company culture that supports it.

Productivity and number of hours worked are orthogonal.

There's diminishing returns, but they are definitely correlated.

Yeah sure, another one of those who claim to "work" 80 hours per week ...

This is why everyone in countries like France, Germany, Sweden, etc. is unemployed.

Sorry, what? This is news for me, I'll go work there in that case

Not convinced. In history as automation has increased working hours have tended to trend downwards.

I doubt anyone smart wants to burn out working under those kind of conditions.

No. They'll be replaced by people who still produce 7 hours of work a day, but take 12 hours to do it, because people like you think butts in chairs are the same thing as productivity.