History means a lot to a lot of supports and clubs, for example, because Nottingham Forest were successful in years gone by doesn't mean much now, as the club is struggling to stay in the second tier of English football.
It does however give the people that turn up to watch them week in week out, old and young the ability to stand and say that their club, once were European champions. That their club, were once was the best club in Europe, and it gives them hope, that maybe one day they will see their club be the best in Europe again.
Chelsea have enjoyed a lot of recent success due in part to the giant amounts of money Mr Abramovich has put in to the club. Success brings a lot of "new" supporters, you've only been around since 1989, so a man who has been watching Nottingham Forest for twice as long has every right to play on the success of the club, or a fan who has been supporting Nottingham Forest since 1995 has every right to play on that success, as much right as you have to play on Chelsea's current success.