"You're not smart, you're just lucky"
I don't consider myself to be particularly successful. There are people who are better than me at my job and there are people who are worse than me but I've made a comfortable living for myself through what I consider to be having a good work ethic and a drive to grow and improve my situation. In fairness, I think there was an element of "right place, right time" in terms of developing my skill set that brought me to where I am today but I'm not sure that I'd attribute that to luck rather than making the right decision to pursue an opportunity that was presented to me. I could have just as easily declined the opportunity and ended up very differently.
This friend in general has only seen marginal success in his career and chalks his (self-admittedly, bleak) situation up to just being unlucky and not having the same advantages as everyone else. I think he's just made decisions that didn't work out the way he had hoped.
So, do you attribute your success and failures to luck, hard work, or a combination of each?