Andrew Bynum was the last 17 year old in the NBA. And by 17 year old, I mean drafted the same year you would turn 18 at the end of the year. For example, if a player is born in 2007, he would be drafted in 2025 instead of 2026. Do you think we will see that anytime soon again? There have been a lot of high school draftees since the one and done rule yet none are 18 (by year’s end).
There are plenty of professional athletes below 18. The NBA just got the players to agree to a higher age limit through collective bargaining.