Luck is subjective – a word that simply defines something highly improbable happening in the eyes of the person using the word. You mention ‘hard work’ as the sole variable that determines ‘success’.  But we just don’t know all the variables that determines our outcomes.  And if you believe in past lives, maybe you worked really hard in your past lives, and it’s not luck at all, but you reaping the benefits of past lives.

As VJ said, don’t get complacent — stay humble, give back to others, enjoy your life, and don’t feel guilty!