The full amount wouldn't be savings. There would also be return on investment. And the stock market has had a crazy decade after the great recession. From June 2008 to June 2016, stock market had an 84% return on investment with dividend reinvested. Someone starting saving this decade may not get the same chance.
I would not be shocked to learn that decent share of those 2.2 million was earned by either mining or speculating with crypto currency. There definitely was some money to be made there in the past 10 years.
https://dqydj.com/sp-500-return-calculator/