I don't believe this will be the route the author would go with this and this is just what I want to happen.
Assuming magic is real in their world, the MC is actually smart, and the brothers really are dead, this is a set up by the sister and royal family that needed MC in power to empower the kingdom. IDK there was a prophecy or something. Too bad this Mc is just a lazy jerk and now he was forced into the head position. But as the series progress, he's digging up dirt on the killers, finding out the motives, while also boosting himself in wealth and power. To the public he's helping the kingdom, but he's really just preparing for his plan to purge the kingdom, destroy the mastermind, and use his wealth to live a degenerate life in hiding.
It prob won't happen. Mc will get a harem and get out of jams with his 500 ig plays😞