Not everyone does research like you. And it is definitely not rude to ask have you heard about x and your thoughts about it, especially if you tried something and it didn't work it could spark a good discussion.
It comes down to two mismatches: first being the famous person's own patience, which is just a normal amount, but instead of usual number of others going up to them now it's 100 or 1000x the number of others.
The second mismatch is the information asymmetry: the famous person him/herself knows that they have gotten 100x people going up to them and saying / asking the same thing, and they know that they will continue getting this for the rest of their life, so they respond with annoyance, which is completely understandable. However, the average person going up to them isn't gonna think that many logical steps and realize this; they're just saying "oh cool, it's a celeb, I never see celebs. Let me try to talk to them!"