It never occured to me that celebrities would start using the platform. I still don't think that Twitter would be anywhere near where it is now if not for the endorsement by many celebrities.
It's hard to explain. I try to understand why the person thinks the idea is good rather than try to figure out why the idea is bad. The realization that most ideas evolve over time also means that the initial idea you dismiss will most likely change.
It's really just about taking the time to better understand an idea, and trying hard not to dismiss it.