Campbell, who played for both Tottenham and Arsenal, was subjected to abuse from sections of the crowd suggesting he was gay.
"I don't think the system is ready for (players to come out)," Campbell told BBC 5 Live.
"I don't think football is ready. Thomas Hitzlsperger, who recently came out as gay, is retired and in a different country.
"He chose to say it now. He is not playing every week and going to stadiums - sometimes fans can be really vile."
Campbell said he believed the abuse he received was down to ignorance.
"Football is such a bubble and if you do not fit into that bubble there will always be people saying things," he said.
"I was very shy as a boy, I didn't want to tell people what I was doing. Most clubs are gossip pits, as I call it, and I just wanted to concentrate on football.
"It is just bizarre. It really is. One minute you move from Tottenham to Arsenal and the next minute people are singing things on the terraces.
"It is quite scary that people take as gospel what is said on the terraces."
