Well you're in a bathtub and the water therein get increasingly hotter. Your body acclimate to it and soon you are there sitting in BOILING WATER and feel just fine. Figuratively of course.
Or alternatively
You are a pool of clean water and slowly by slowly it becomes a CESSPOOL. You are thriving in it. Now had you been thrown into a cesspool without any prior acclimatizing you might just die instantly.
Can the poisoned acclimate to being poisoned? Introduce a bit of poison into the body every day and soon it cannot exist without its daily ration of poison?.
How else do you explain what has happened in America SPECIFICALLY to the Republican Party? Or is it rather that a curse has been placed upon it?