The Contgress approves the money, If the president squanders it, I as a member of congress would certainly not approve a raise.
WRONG. Congress spends. The President carries out legislative bills congress has passed. If congress spends which they do, which is normal they must pay .... it's so simple.
You do know those bills quite directly state what the money is to be spent on. NOT the President. It's his reponsibility to make sure the United States pays the bills that congress writes then executes .. which entail spending .. except when they name toilets reagan.. etc..