I try not to get my expectations set too high when it comes to cheap switches. It is expected that a doorbell switch will fail after long exposure to the elements. Most are inexpensive, one replaces them and moves on, but to make a $40 doorbell replacement is a hard sell. I have replaced a number of these items. In the majority of cases the cheap little button switch is the cause of the failure, but the whole assembly needs be replaced.
Use some clear silicone caulk after connecting,(AND testing), the assembly to seal the rear of the switch, and to seal the housing to the wall. It will not stop the button from failing, but will extend the life of it.