Why are you trying to obtain a discount on the cost of software development by obtaining two employees worth of work from one employee? I mean, that’s the honest question?
If instead, you ask, “why do some programmers like to work 80 hours a week, and others do not?” It’s because if you’re working on a game program, or something that is passionately fascinating to you, then you’d rather do that than anything else. But you cannot possibly make most programming that interesting.
I work easily 14 hours a day between my occupation and my avocation, and often much more, and usually six or seven days a week. But I both have the physical and mental capacity to do so (mostly), and I would rather do my vocation and avocation than I would do anything else.
The number of people with the (a) physical, (b) mental ability, plus treat programming as both (c) vocation and (d) avocation, and who (e) prefer doing very little else – is just limited.
So, just as very few species can be domesticated, because they require compatibility in five different behavioral traits, very few programmers (or people in general for that matter) can work that hard that much because all five of the criteria a,b,c,d and e, must be met to get that from people.
Money actually won’t do it, only make it easier to do. Opportunity helps motivate a little. Love of what they do helps most, and the individual’s genetics are the greatest determinant.
But, if you think you can ‘motivate’ people into working those hours the only way that I know of is to do it for six weeks or less, and bonus EVERYONE Involved something life-altering if they achieve the goal, after which they get a vacation for two weeks. Why? Because social membership will drive people more than any other factor – at least for short periods of time.
If you put such an incentive together, anyone who doesn’t carry the water of the whole team – fire immediately, and keep the rest. Otherwise they poison the well.
But it’s an illogical man that seeks to obtain two people’s worth of labor from one person. I mean, that’s not only fruitless, and marginally impossible: it’s immoral.
Which is why so many countries forbid it.