I think the reason we adopt this mindset is because we are ambivalent. First you feel you wanna go, then you regret it because you are nervous about the rental car, then you wanna go again, then you regret it because there's a lot of stuff at work you want to deal with, then you wanna go, then you get scared of skin cancer from the strong sun etc etc

Booking and cancelling and booking and cancelling and... It would be terrible to change your mind so often. So you decide to just go with the option you picked first even though it temporarily seems suboptimal.

It's suboptimal to continually change your mind so rapidly too, not just 'terrible' mentally, because the real world around you imposes significant penalties for doing so.

Switching flights and hotels on a moment's notice is expensive. Arbitrary days off work are difficult for most. For some travel you're looking at visas, rental cars, etc as stated.

There's a lot of inertia in the boring and stable path.