system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] What exactly makes an unhinged, evil Doctor more dangerous than say, the Master?

The Doctor abandoning his morals and rules is always treated as basically a threat to all of existence. The Master is like this all the time, is clearly shown to have a similar level of intelligence to the Doctor, and yet isn't regarded as nearly as big a threat to everybody.

I know there's the reason "The Doctor is there to stop the Master, if the Doctor goes bad, who stops him", but the Master doesn't spend all his time opposing and being stopped by the Doctor, right? 

There's surely stuff the Master does in his personal time that results in lives lost, worlds broken and civilisations enslaved, and yet its never treated with the gravity that I feel it deserves.
gpt
Think of the Master and the Doctor like Batman and Joker. While the Joker is incredibly destructive, most of his destruction is done to and for Batman. But if Batman snaps the Joker isn't going to stop him and there are very few people who actually could. If the Doctor decided to take over/destroy the universe the Master would most likely cheer him on and see it as a victory, there'd be no one with the power to stop the Doctor.  Even if the Master tried we have seen multiple times he can't defeat the Doctor.