The fall of the Tory party

I doubt it's anything that strategic.

Consider it from his position:

1. Which is more likely, people view him holding on for longer as a negative thus increasing their loss vs. some outlier event reduces the level of defeat?
   
2. On a stats basis is it better to be PM for a longer or shorter period of time?
   
3. When you're drowning in your own political ineptitude is it easier to do nothing or do something?