He has actually tried to cut spending through various ways like cutting the government budget for many departments and substantially lowering foreign aid by billions. However, every time he wanted to decrease the budget for government entities, the people with opportunistic outrage would fight him for it saying he was killing kittens or some other something. Since congress ultimately controls the money the US spends and you need a supper majority to overcome the opportunistic outraged people who can cause a government shutdown, you can't cut a budget unless they agree. The tax cuts were suppose to be paid for by government cuts and removal of the very costly AHC, but some don't want us to stop wasteful spending because they believe more government is better.