Image: UbisoftOfficial screenshot from Ubisoft.
This Vaas: Insanity trophy asks you to escape Vaas' mind at Mind Level 5, the hardest setting. It takes several full runs, which is why so few players have it.
Escape Vaas' mind once to open Mind Level 2. Select it from the Add-On menu, beat it, and repeat until Mind Level 5 is open. Finish one more full run at level 5.
Max out your Mirror Traits before the level 5 attempt, especially Pride for health and Greed for Cash retention. Unlock all Weapon Cases first so you can buy your favourite guns right away. Play slower than usual and lean on stealth, since enemies hit much harder at this level.