We do not think of the impossible, focusing less on ‘reality’ than the ‘thinking few’. We are idealist because we do not yet live our Utopias.
With the discussions around capitalism being inevitable and a better, more ‘possible’ condition than say, Anarchy, it is almost difficult for the utopian few to miss the signs of privilege. Of course a capitalist system would work and serve everyone – it is its intention to survive. It has been made human.
As Zizek suggests, happiness is an unethical category. When your utopias are achieved, they cease to be worth maintaining.