The 18 year-old defender left Parma for Liverpool on Friday.
Reflecting on the move, Fascetti told TMW: "The English have a keen eye, they're not stupid. It's a shame he left because he's an excellent player and will do well in England too.
"For a guy like him, 35 million (euros) isn't a lot, and our teams shouldn't have let him slip away."
Fascetti also believes Ademola Lookman will now stay with Atalanta. Despite his very public transfer demand, Fascetti says the broken bridge can still be fixed.
He added: "I'm convinced an agreement will be reached; this confrontation isn't in anyone's best interest. Of course, if he still has a contract and is acting up, I'd intervene drastically.
"Enough, these players have too many advantages. You have a contract, so if you want to play, you play for Atalanta, then we'll see next year."