It’s mostly luck, but without hard work there is high decrease in luck. But mostly it’s just a luck in an environment: from social to biological, but even then the luck plays a huge role in obtaining success.
Not accounting the luck seems to be major flaw in realizing how lucky one is.
Luck seems to be overshadowed by the hard work and skill, when that is all is seen and felt while obtaining the success.
That is why successful people see the less successful people as not enough hard working and make up things like: not being worth of their generosity and therefore not sharing the help for the less successful.