Yep, luck.
I'm the child of a single mom of 4 who made $7000 / year, and I'm the first of my extended family to graduate college and the first millionaire (my younger brother got to middle class). Luck is the way that I succeeded.
1st, being born with a high IQ helped. But, that clearly wasn't enough since I had the lowest IQ of my family. And, 40% of my gifted class didn't even graduate high school.
2nd, being born with a personable and friendly demeanor helped a lot, probably more than my intelligence. However, by having intelligence, I was better able to make good choices of friends.
3rd, being born with height potential was huge. It's been clear to me that people in powerful positions are much taller than average.
4th, being born with symmetric features and attractiveness was important. Again, this attribute helps in making and keeping relationships. And, when people think of someone, they often think of me first.
5th, being cautious and risk adverse was hugely important. I was involved with the gangs and criminal activity like many of my peers, but I was extremely careful about what things that I would do. Also, many of my peers ended up having kids in their teens, which was very devastating. Many became addicted to drugs and died. Many died of accidents and suicide. Of my friends, over 15 died before I was 25 (I lost count).
6th, having a mentor was good for me in making good life choices. A retired, highly educated engineer took me under her wing and mentored me in my late teens. Before I met her, I had not even considered going to college. I looked forward to being a manager at a retail store. Even though I was in the honors and gifted program and ranked #11 out of my class, I never once received any college guidance from my school. So, her help was amazingly helpful.
7th, (sorry, this is getting long), living at a time when college was affordable and accessible was critical. I went to college in the 90s when tuition was under $2500 a semester, and I was accepted with many marks on my academic record. Even though I wasted time in college, I was able to graduate with only $40k in debt.
8th, picking the right major was extremely important. I floundered around for a couple years at college and almost dropped out. Then, I had a roommate who turned me on to computers (I never had one, since they were very expensive). I took a couple programming classes and found it to be a creative outlet. And, at the time, graduates were making $30-45k, which seemed great to me.
But, looking back on it all, it was mostly luck. I wish I could say that I had some part in it, but really, I didn't.
The only very important (maybe most important) decisions that I made didn't happen until I was over 30. I moved to a wealthy area and I married up. Without doing those things, it would have been much much harder to gain access to connections and capital.