Those aren't necessarily your best guys. Those guys might have to work more because they are spending too much time messing around, and not being productive.

Personally I like to give it as much as a can for a solid, honest, 8 hours and call it a day. This way I can give it my all everyday, and still get the R&R I require.

I don't think there's much correlation between how much someone works and how good they are. I like to think I'm pretty good, and I work 8 hours a day, and some of my coworkers are also great and work more than that. I generally value my work/life balance a lot and really don't like exceeding 8 hours a day/40 hours a week (and can feel my productivity drop after roughly those amounts of continuous work), but this is probably mostly a personal matter.

I don't let other people's working longer hours than me affect me, though, because I know that my total productivity would decrease if I worked longer hours. If that's not the case for other people, or if they like work so much that they want to do more of it, or if they are bored in the evenings/weekends and want to dabble in something, that's great for them.

I think the factor that helps is that I don't have management that will say "yeah, but X worked 60 hours a week and you didn't", but I'm pretty up-front about that anyway, and just stand my ground.

All that having been said, I do find the US work ethic a bit crazy. Working crazy hours isn't good, and the amount of hours worked per week isn't usually proportional to productivity.

For how long? When do they burn out? What happens when they burn out? What happens to the team, project, product, company, customers, their families?

Or they work best alone and seek their solitude off normal work hours, producing code with no shared ownership, effectively creating a liability for your company.