It is totally luck, combined with genes and having the right circumstances/background.
All these things can make ot break a situation, a career or a life, and of course, people can become successful through sheer hard work too.
But..my publishing career was going great until I had a head injury and post concussion syndrome a decade ago before being injured permanently by an off label antipsychotic prescribed for severe insomnia and anxiety 😳 Consequently, I now have a movement disorder called tardive dyskinesia that is a bit like Tourette's and Parkinson's disease combined 😢
Plus, I lost my ability to read and write after my head injury... not great for an editor. A good upbringing, very loving adoptive parents, a degree etc, plus excellent health before being injured all made bugger all difference to my career and health problems now.
Being fit before didn't prevent being unwell. I totally agree that health is wealth. If I could turn back time and be that person 12 years ago before being unwell, my life might have been very different.
But, it just is life. So I carry on.
I agree that most people are potentially able to achieve something good in life. Whether life lets them do this is another thing entirely.