When you think about it, there is no such thing as irrational.
There is something that is irrational... to YOU.
To me, it might feel like the rational thing to do.
As this is the same for you customers, your users, your friends and your parents.
The trick is to see the purpose and benefit behind what you see as irrationality in the other person.
Then you understand their decision, and you can set up a system such that there is no longer a need for it.
Or you can help them achieve that benefit, elsewhere.