I've been thinking about how to respond to this question and have read the meandering discussion with interest. I guess it depends on what you call a head start. Being born into or moving to a developed country would seem to be the biggest factor. Having parents who cared for you is also a big help.
My parents would not pay for college and made too much money for me to qualify for aid other than loans, which I had zero interest in (get it?). I also had five stair step siblings right behind me. I got a job and went to work immediately after high school. I worked full time the first semester and started Junior College in the spring. I worked as many as three jobs and earned a number of small merit-based scholarships to pay my way. After I got an AA, it was my plan to work for a year, declare myself emancipated from my parents so I could apply for need based scholarships, but the universe laughed at my plans.
Just a few months into my new "career" job (Starting salary in 1978: $13k and a company car. Woot!), I was diagnosed with cancer. The company was so good to me while I was going through treatment that I decided I was going to stay for five years as a way of thanking them for their generosity. At the five year point, I decided I wanted other things on my bucket list more than going back to school. I also knew I could never go without health insurance. I decided I wanted to buy a house more than I wanted to go back to college. I never did get a four-year degree, but I did get my house, and many more since then.
I stretched my nose over the $100k salary finish line exactly once in my career. I was self-employed at the time and that was before taxes or expenses, so I wasn't exactly a high earner, especially compared to a lot of folks around here.
What I was was determined. I was determined to enjoy life as I was living it, because the future was not guaranteed. I was also determined to save like mad to meet my goals and retire early. The term FIRE hadn't entered the mainstream lexicon, but my Dad was a gub'ment employee who retired at age 50 with 25 years of service. Except he kinda had to, because he was an Air Traffic Controller with a wife and six kids to support. It was 1981 and he was not about to cross a picket line, so he retired. I knew if he could do it, I could too.
I consider myself privileged because I had two parents, who stayed married to each other, who loved me and my many siblings. I had an excellent primary education, with a few outstanding teachers. I was smart and good in school. I was also blessed with a long, lean frame and attractively arranged features. Yup, that's worth something, and that's as messed up as it sounds. Is it the kind of head start you're referring to? Dunno. But there are plenty of people who have been given far more and ended up with much, much less.
It doesn't matter where you start; it matters where you end. Where you begin is largely a result of genetic roulette. Where you end up is far less random.