Why are US Customs CBP agents such pigs?

Every time I return to the US from travel abroad I am greeted by the dumbest miserable imbeciles in the planet that only want to cause unnecessary pains to all travelers. No matter where in the world you travel you can't find more idiotic border agents than these b...rds. Why are CBP agents such pigs when most countries have border agents that welcome you and treat you like a human being?????