It's more about outlook on life than luck.
DH and his brother had exactly the same upbringing, same school, same parents, same everything. No disabilities. Both equally intelligent. His brother was never interested in schooling, left after GCSEs in about 1986 and started work in a local insurance company. He's still there. Never really progressed, never wanted to progress, never shown any interest in moving on, doing training, anything really. Any opportunity is treated with suspicion and fear. His salary hasn't really moved on much, he's still on around £20k, his wife works part-time, and they're constantly short of cash.
DH on the other hand stayed on and did A-levels, went to Uni, moved away to do so, moved again to a new city after graduation to take a job, made it known that he was up for further training, put himself forward for 6 months working on a project in China, moved jobs several times, more money every time.
Now it's fine not to have ambition and want to work in the same place your whole life. But DH's brother constantly goes on about how lucky he is, how it's "not fair" that our family income is about 5 times what their family income is, how DH gets to do all these cool things at work when he is doing what he did when he was 17.
But BIL could have had all of those things too, had he been prepared to put himself out there and go after it. Opportunities don't force themselves on you, you have to go out looking for them, or at least be prepared to seize them when they present themselves.