Perhaps true, though working-smart and being affable/networked seems more important than grinding. Still, IME, that variable amount of luck is tiny relative to ‘starting luck’, or straight blind luck.

I think it is fair to say that luck ‘compounds’ like interest. Being in a good position generally confers more frequent and higher-value opportunities to get into a better one. Getting lucky early is very important, and the earliest luck you can get is the circumstance of your birth.