Nicolino Berti I believe attends almost all games
Didn't Sneijder attend a few? Or was it just the one at Curva Nord?
Cambiasso I think was a frequent attendee for years after his retirement, maybe still is.
I'm sure there are quite a few, mostly Italians of course. But we don't have a lot from the 2000s and 2010s that'd be there.
Cassano, Adani, Ventola who are part of Vieri's Bobo TV crew all have an attachment to Inter and you'd see them there whenever they can make it.
Vieri spent most of his career at Inter, and I think as an Aussie raised Italian without strong fan influence, he wouldn't really have a favorite team growing up even if he claimed one. If you ask him today, he'll say that he loves Inter the most out of the clubs he played for. And it makes sense. He hardly got attached to anyone else.
He also said he likes Atletico a lot and didn't want to leave. I think he also said when we got the contract termination he first asked to return to Atletico but they didn't have space, nor could afford him to be a rotation guy. So he went to Milan because of proximity and because Galliani persuaded him, even if he knew that it'd be considered a dick move towards Inter and Moratti.
I think their beef ended a few years after that, they should be on good terms now I believe. Moratti got paranoid with Cannavaro and suspected everyone.