Haha yeah you keep droning on about that. Except no Ajax supporter is hurt by that premise, like there is some rule all Ajax players must have played for them since age 9, or else they are not worthy.
In reality the fans are proud Ajax picked up an obscure youth player from a small team which didn't even play him and were happy to sell him for scraps, and developed him into a player worth 75m euro who is the first player on the team sheet in the Dutch team. Excellent vision.
Aaah Feyenoord. Frenkie is from Feyenoord land, his family were Feyenoord fans, but he snubbed Feyenoord as a pre-teen over Willem II because he thought that was a "warmer" club. Feyenoord were sleeping again when he turned 18. And now his family are Ajax fans.
^ That's how you properly do it