Obviously, luck plays some role, but its just hard to quantify.
There's obviously the genetic lottery, and its hard to argue that someone who has born with degenerative issues or other disabilities that prevent them from reaching full potential is 'less lucky' than someone who is born healthy. Not a lot of personal choice there. So for that, I certainly feel lucky.
Then comes the environment that you were born into, and this is probably more up for debate. I feel like being born as a white male in America, to two parents who provided me a stable environment counts as "luck". when it comes to my financial success. I certainly didn't choose those things, but nonetheless I feel like they certainly helped me achieve the success I've had today. Once again these weren't choices I made.
After that, i suppose it gets more murky. Obviously I feel like that the choices I've made and the work i've done start to account for my success somewhere along the line.I like to play poker, so for instance, you might get dealt pocket Aces, which is an incredibly lucky hand to get, but you can't win unless you play them.. so I decided to go to school, get good grades, get a job, do well at the job, start savings money etc.. But, i feel like its important to remember that I got a good head start (Pocket Aces, well maybe Ace/Jack in my case) at the biological and environmental level.
Obviously sometimes you lose when you get pocket Aces, either because of bad luck and/ or you played them poorly, just as sometimes you win when you get dealt Seven, Deuce- either because of good luck and/or you played them beautifully. But, it's still easier to win with the pocket Aces.