"Luck" is a catch-all phrase used by people to describe forces they don't understand, or that they feel are beyond their own control.
Most of the time it is used from the outside looking in, as in "He's so lucky." or "He didn't do anything special, it was just luck."
You can choose to believe in luck, or not.
One thing I heard about luck long ago is the harder you work, the luckier you get.
Or you might say the smarter you work, the luckier you get.
I'm the luckiest man in the world.
Thanks for asking.