De Rossi was sacked and replaced by Ivan Juric at Roma on Wednesday.
Sabatini posted to social media: "I am bitter. Years ago a notable in the environment said something that I can agree with: football is a stupid game for intelligent people.
"Today only the first assumption is valid and it is useless to expect that we could have noticed the improvements of an experimental team and it is equally useless to expect that they realise that they must acquire football and general culture by hiring with full powers profiles like Boban and Maldini who three years ago, together with Massara, gave life to the refoundation of Milan that led to the Scudetto in a very short time.
"But De Rossi fired, no, it can't be done, someone is living in a delirium of omnipotence."