I am absolutely convinced that Trump’s entire election strategy was to just coast to victory on “Biden old” and “I got shot”. By the time of the republican convention he was confident that he had it in the bag and didn’t need to keep trying, so when Biden dropped out it completely shattered his plan and he’s got nothing to replace it. He does not have the cognitive ability to pivot against Harris/Walz and his ego is way too big to actually listen to his campaign strategists (if he even has any that aren’t just yes men).
this should not be interpreted as complacency. It is definitely not a sure thing that Harris will win