Campbell, who has been married to interior designer Fiona Barratt-Campbell since 2010, was targeted by homophobic chanting during his own playing days despite always denying claims he was gay.
Speaking to Victoria Derbyshire on BBC Radio 5 Live, Campbell said: "I don't think they are ready, the system isn't ready for them.
"I don't think football is ready - some of the authorities might say they are ready but I don't think football is.
"It was quite strange that people actually took what was said on the terrace as gospel, it is quite scary really the type of things which are chanted and intelligent people listen to them."
Former Aston Villa and Germany midfielder Thomas Hitzlsperger came out in January but Campbell feels it is easier for an ex-professional to take such a step.
"He has retired and is in a different country," 39-year-old Campbell said.
"He chose to say it now and he is not playing every week, he is not going to other stadiums, sometimes fans can be horrendous, vile."
Campbell's brother John was sentenced to a 12-month prison sentence in 2005 after attacking someone who had labelled Sol as homosexual.
It was during this time that Campbell struggled with the claims surrounding his private life.
"I'm from a big family," he added.
"It is tough, that is when it started to affect me because my family got involved. They didn't have the support system, a big PR system to help and protect them.
"We were just a simple family growing up in east London. They didn't want or deserve that.
"Maybe people didn't really get me. Football is such a bubble and if you don't fit into that bubble, if you don't fit around football, there are always people going to be saying things."