Why do I value menial tasks?

I find that after accomplishing something difficult, I like to schedule more mindless tasks. Why?

The world is full of mindless tasks.  Pointless choices, What to buy,  How to spend money,  Bureaucracy  Exams. 

The common thread is this: 

All these actions are good for the collective, at the expense of the individual. All these actions are altruistic. Of course, you may have something to gain too. But overall, it's kind of a loss for you.
I think it's because deep inside, I derive a kind of security from doing this. The fact that I have time for this indicates that I am in a secure place. 

I know it's dumb, and I want to change it, so I'm still figuring out this habit.