A wealth manager for very wealthy makes a distinction between top 1% and top 0.5% (8 million according to IRS and 15 million according to the Feds). The top 0.5% is reached only by people with inherited wealth, or very lucky people who get to top 5% by smartness and hardwork, and end up in 0.5% due to good fortune, or stock options. Professionals, doctors, lawyers, accountants are very unlikely to reach top 0.5%, and increasing not even likely to reach top 1%. He used to see very successful professionals retiring in top 1%. But no longer.
He calculates that a person starting at low end of 1% by income for that age group, and staying at the same band (99% dividing line by income) all his/her working life will NOT end up in top 1% by financial wealth. A persons starting in the low end of 1% by wealth, will stay there if he/she draws the same amount of money our 1% by income professional, and might go up in scale.
In USA money earned by blood, sweat, tears and brains (wages, earned income) is taxed at much higher rate than money earned by money (capital gains, carried interest, qualified dividends, etc). This is the root cause of the inequality. For 30 years, since Reagan, the US Govt has been coddling the super rich by funneling all tax relief to them. They turned their back to the USA, invested all the savings in low wage countries to maximize their profits.