How to explain the Congressional death march.

The writing is on the wall. In 2016, the House lost 9 more Republican seats and the Senate saw female presence increase to 20 seats. Seniority, upon which power has traditionally rested, is on the way out. So, this is their last chance to make mischief and express their displeasure with an electorate that sent a numbskull to the White House.
“Après moi le déluge” is not necessarily an expression of disinterest. Rather, it is just as likely a matter of intent. “As I depart, I’ll leave a mess behind.” That’s probably what the Unjust Steward in the biblical parable, anticipating revenge, said to himself.