>> to become a radiologist so probably pays a decent amount in taxes now.

Specialist doctors are one of those jobs that is on the cusp of tax planning/avoidance technology. Once you are touching 1mil per year you have enough money to engage proper tax professionals to take care of your money. In the US they will run their practice as a business rather be any sort of employee. Offshore trusts, spendthrifts, deferals ... I wouldn't assume that every doctor suffers a huge tax bill each year.