Whom would you impeach? The entire U.S. Congress?
Why would Congress be so derelict? Because we let them. Representative Paul Ryan has been pushing a good plan for cutting U.S. government spending. He has found little support in Congress. Why? Because Republican and Democratic politicians are convinced support for the plan will prevent reelection. The U.S. Congress spends as it does because we let them get away with it. Why? Because we make dumbass arguments like, "but we can't let the Democrats/Republicans win." So we keep voting for people who by and large end up supporting massive government spending and we never hold them accountable. We let Congress refuse to reign in spending because we can't talk about cutting spending on programs like Medicaid or Welfare, or because we refuse to discuss the possibility that U.S. military and U.S. law enforcement spending is done in massively inefficient ways. The U.S. government "awards" this or that contract for building this or that thing for the military often not because the military needs it but because it wins votes for the Senator and/or Representative in whose state the thing is built. Then there is the war on poverty. The war on drugs. "We need a wall on the border." Oh, and perhaps the one in most favor right now, job creation. Every politician has a plan for how to spend lots and lots of taxpayer dollars to create jobs, as if the government can actually create jobs in the private sector. So we keep voting people into office, at all revels really, who run on how they are going to spend money and how they are going to protect and grow other spending programs. Until that changes, impeaching Congress would do no good at all.