//I really cannot understand the mindset of any football fan (however old they may be) abusing footballers because of their colour.//
The abuse isn't about their colour or racism per se, it comes from a place of 'hating' players from other teams and trying to make the most hurtful comments possible to them - of which which racist comments are easy and up there in terms of impact.
Everything is fair game, a players child who died, their family, anything that will cut deep. They derive pleasure from this along with notoriety amongst fellow fans, especially if it gets a reaction from the player and even better if it affects their performance negatively.
There is racism in it that's for sure, deep down they will think their own players are "black ****s" for sure, but if they score the goals for the team they support then who needs to worry about it - but just wait until they stop performing well, or even worse go to another team.
Football has a real problem with this that is not seen in other sports.