There's a difference between Eagle fans and Eagle fans that live in Philly. lol... It's a culture, right? I think this is what most people don't get. It's an identity for them. My dad grew up in Philadelphia in the 50's and brought some of that attitude here to Delaware with him. Now the Eagle fans around me are family and of course don't have that Philly DNA triggered. Usually by those in Philly its not malicious and to an extent meant to be funny... like booing Santa... Sometimes it's just being crass and letting your inner jerk out. Even the egg thing doesn't really cross the boundaries of mischievous.
Are they bad people/fans?... I don't know about that. Most are loyal diehards. Dick Vermeil is still respected so that should give people an idea that the people in Philly respect integrity. The irony is that lacking integrity is kind of like their brand of fun, and they know it.
I was at a game in Philly in the 80's I believe. Bartkowski got destroyed and laid motionless on the turf... after a few minutes the guy behind me shouts "Scrape him up. Get him off the field", lol... about as low class as you can get. I was a teen then but looking back on it, I'm pretty sure he was just being a Philly type of fan. Probably not serious but determined to be crass.
Now, at the same time, yes there are plenty of jerks in Philly. When we went to Phillies games (again in the 80's) my dad would yell "You bum, etc...." at the pitcher. I don't know, almost like it was his right, lol. I'm not staying I know Philadelphians but that's the way I see them.
I will say this. We went to Syracuse to see the eclipse a few years ago. And on the ride home, you could tell you were getting closer to Philadelphia because of the way people drive. Not just aggressively but sometimes it seemed just to be a jerk.