How come footballers get criticised for wage demands?

I strongly believe in market forces with demand and supply dictating et prices,salaries and other tradeable contracts. Sure there are market failures but I believe this is the best available option. My question is why do footballers get so much abuse for earning a lot of money. I am an Arsenal fan but I fully support Wayne Rooney for wanting to get a higher salary. It is easy to say that if player A is earning �6 million a year then why should he need �8 million a year but then it is relative in that a person in one part of the world earning $1000 dollar a year may question why someone wants to move up from �60,000 to �80,000 per year. Irrespective of what is considered morally appropriate I think most people would want to maximise their potential earning power. It is not as though footballers are doing something illegal. It just so happens that there is a huge demand for these scarce commodities (i.e. footballers) through matchday revenues,broadcasting and commercialisation primarily. The worst argument is when people criticise them for earning "astronomical" wages for only kicking a leather ball for a few hours a week. These guys have dedicated their lives to becoming the best at what they do. Surely if anyone could do it then the wages would not be so high as market forces dictate that the greater availability of footballers would drive down wages. Clearly not the case. Happy to hear views from people who agree or disagree.