I would think the same if I didn't experience the opposite. To be honest, I would start with an email / linkedin mostly, but even cold cold calls work. I remember doing exclusively cold cold calls for one side project (airbucks.io) - and I got an awkward early ending to the call maybe 1 out of 5 times. Which doesn't faze you much when you've just had a blast for 30 minutes with a potential customer.
I guess if it's something that's genuinely interesting, it's the same kind of flattering as if a crew/group of students with a camera accosts you on the street to ask your opinion on something. I'm happy to provide feedback if it comes with no requirement to pay.
Totally agree! People's willingness to tell you about their thoughts is the N.1 way to get a call started.
Now imagine that group of students opened the conversation with: "I saw you raise your hand in C101 this morning, and thought your question was very interesting. What made you think of that?"