So Endeavor is canonically 45-46 right?
And Dabi/Touya Todoroki is 23-24.
That means that the absolute OLDEST Enji could've been was 23 when Touya was born.
Rei would've been pregnant for 9 months so we'll assume he was 22 when he got her pregnant.
The big 3 are proof that you graduate UA at 18-19 years old, and we're gonna assume he was an instant sensation.
Which means Enji was a hero for less than 5 years before he gave up on trying to beat All Might and decided to use his children to do it instead.
LIKE BRO DID YOU EVEN TRY ANYTHING ELSE?! 5 YEARS IS NOT LONG AT ALL TO BE A HERO!!!