Is it wrong to be 'selfish' at work?

I actually find this to be an interesting topic and something I think about constantly.

I've always tried to balance personal ambition with personal sanity, but even that has evolved as I've gotten older and gained more confidence.  Starting out, it was insecurity that drove going above and beyond.  Sure there was satisfaction from putting in so much effort but it was mostly centered around a strong desire to prove myself (and an unhealthy fear of being fired, to be honest).  Now with experience under my belt, I don't feel like I need to run around with my head cut off to prove value.

The two biggest variables that play into this, in my mind, are (1) Will going above and beyond be rewarded? and (2) Do you care about the rewards?

Incentive drives behavior and if you're in a spot where doing more will directly correspond to advancement, more dollars, etc. then it's a question of whether or not you care about the those things.  If you don't, then there is nothing wrong with thoroughly covering your bases, but doing nothing more.  If you're in a spot where it's not rewarded, you could argue you're a fool for making your life more difficult and you should probably look elsewhere if you have those ambitions.

These are just perspectives, maybe even obvious ones... I don't believe there are hard and fast rules on how to operate because everyone has their own ideas of what matters to them.  It varies based on life stage, work environment, and personal goals.  The key is to have awareness around each of those things and use that to make a decision that provides you comfort.