Just thought of;
We been satta’s since no discernable beginning which means we been doing Sakkaya Samudaya. Avija and the 4 other causes in Sakkaya Samudaya causing the 5 effects, would give rise to a satta. As long as a satta has avija, the perception of a “self” will always be there since this perception of a “self” can be equated to avija. It seems like Sakkaya samudaya is what causes/give rise/ maintains Sakkaya ditthi while Sakkaya ditthi in turns fuels/feeds Sakkaya samudaya, feeding each other.