Why did you send this email to me? - He asked

I would probably tell him why.

Did you make it clear why were emailing him in the original email?

@"Simple As..." Yes, I did. He is asking me why I chose/emailed him specifically rather than someone else. I picked him randomly, and obviously I cannot tell him that. What should my response be?

Just find something that you may have in common with him. Have any sort of connection to a school he went to? Grow up in the same state? Interested in his group's sector?

If you can't think of anything, maybe just say something like "I thought you would be a good resource for...yada yada"

@"parctribe" Group`s sector is only thing that is in common, nothing else. He is probably asking me why did you pick me rather than other associates in his group. He most likely wants to feel special, lol. No one had this kind of response before?

@"Simple As..." He is not an alumnus. Well said!

Just tell him he seemed like a good guy that you could see yourself having a beer with

I don't think he's being mean, I think he's just being direct!
Maybe just say you "wanted to emulate him in his career and that's why I sent this email, to understand how you went from grad student to BB analyst..then Associate(If that is how he became Associate, or maybe you should ask him how became Associate)?.

I wish someone cold emailed me one day :)....actually maybe not I can barely get through my 150 + work emails a day don't think I would even pick up on it

I haven't had much experience with this. My school has a lot of alumni so it's often not hard to find a connection at a firm in my target industry (consulting). Don't read too much into it, maybe he thinks that you may have met at a recruiting event or were referred by a mutual friend, and therefore doesn't want to embarrass himself for not remembering.

How did you find his information? Just going through names or was there a particular site that would be a commonality?

You could do the brushoff-answer as parctribe said. Something like "I have a deep interest in ABC and would appreciate any insight into that group you can share."

@"Blueapple" I am interested in his group, so I directly copied his email from their website I came across.

Good luck buddy! Sorry you had that kind of response.

happened to me like 5 times man, no worries, just email him back that you're really interested in his group.

2 of the 5 went on to talk to me, since its still a chance.

tell him that you want a job