I think it's related to post-purchase rationalisation. People are emotionally wedded to the tools they use and the paradigms they operate in because changing (or, God forbid, "catching up") implies they've somehow miscalculated or invested their time incorrectly.
Especially in the tech scene, a lot of people see themselves as unappreciated geniuses. The idea that there's a good, simple alternative that will get mass adoption that they haven't thought of doesn't fit that narrative. There must have been a reason they already dismissed the idea, so they approach it skepticism. (The money thing is related to this - unappreciated geniuses deserve a good get-rich-quick scheme, after all.)
Especially in the tech scene, a lot of people see themselves as unappreciated geniuses. The idea that there's a good, simple alternative that will get mass adoption that they haven't thought of doesn't fit that narrative. There must have been a reason they already dismissed the idea, so they approach it skepticism. (The money thing is related to this - unappreciated geniuses deserve a good get-rich-quick scheme, after all.)