How much of success is luck?

At least 50%. Speaking more authoritatively based on personal experiences, it's even higher. Hard work matters no doubt. But, with luck on your side, the same hard work will yield far more positive results than otherwise.

The kind of environment you are in or/and have grown up in, pretty much completely sets your luck.

There is a reason innovation is directly proportional to supporting environment. There is reason that developed countries produce far more innovation than developing ones, even though people in both places work equally hard.... The surrounding environment.

The thing is, you don't control surrounding environment. You are born or placed into it by default. Some people can move between environments, but, that itself is influenced by environment. Money, access to right people at right time, correct guidance, macro economics, etc..

Every single act of luck can be answered by surrounding environment. You want to change your luck?.. Change your environment.

2009

Everything requires some luck, so it's moot. I find the people saying this are trying to find a way to cut down anyone that is successful.