In a European country, think Spain, Italy, France, "get good grades, study a valuable major, don't eat garbage, don't marry crazy people/idiots, stay off dangerous drugs, and mainly show up to work, be clean and nice" and you are likely to end up with job paying 40 to 80k (before taxes) a year, which is not bad, but I consider that money far from financially making someone "a very successful 40-year-old".
With my STEM major and a PhD, I would have made between 40 and 50k per year before taxes.