Homegrown fighter plane development and production is expensive, They get fighters from USA at massive discount and their industry also takes part in upgrading these planes and that is enough. Their last fighter project was cancelled, basically because USA refused to co-finance it.
Aside from money, their defence research and development capabilities are limited (9 million population, with large percentage being useless in this regard) and spread across multiple fields (armour, ATGMs, SAMs, AAMs, electronics...), which means their aircraft industry would have to rely on technology transfers or imports, while also shortchanging some other fields of military development.