We could do worse than Trump... But.... We could do a LOT better too. I sure hope Trump get's tired of spending his money on this side show pretty soon...
The summary nature of voting on legislature (yea, nay, abstain) puts an upper bound on the amount of damage a bad congressman can do.
Essentially, there are a finite number of times any congressman can vote on an issue. If they vote against the interests of the people every time, they've reached maximum damage.
The same can be said of presidents (pass, veto, pocket-veto, &c.).
Few issues are black-and-white: most laws are some percent good for the people and some percent bad. The two issues I can find that are closest to 100% bad for the people are H1B Visas and the Patriot and USA Freedom acts.
H1B visas take jobs away from Americans and allow corporations to impose misery on the imported workers, and the Patriot act and related violates our rights and makes us less safe (by diverting resources away from effective strategies like intelligence gathering).
The relevant votes are shown below. The government doesn't care about our rights, and it doesn't care whether we have jobs. It has reached maximum damage.
Trump might be the worst president we've ever had, but at this point in time, he's not *guaranteed* to be the worst.
USA Freedom Act (Senate)
YEAs: 67 (D = 43, R = 23, I = 1)
NAYs: 32 (D = 1, R = 30, I = 1)
Not voting: 1 (R)
USA Freedom Act (House)
YEAs: 67 (D = 124, R = 179, I = 1)
NAYs: 32 (D = 70, R = 51, I = 1)
Not voting: 2 (R) 5(D)
Increase H1B Visas (Senate)
YEAs: 67 (D = 52, R = 14, I = 2)
NAYs: 32 (D = 0, R = 32, I = 0)