It was a sarcastic post, we Man United fans call you a massive club because everytiihng about you is massive (goalposts, ASDA store next to you stadium) If you lived anywhere near Manchester you'd know how to take the joke.
And money isn't everything to every player, as proven by Kaka rejecting you just a couple of weeks ago. The Club may well accept the offer, but it's down to the player at the end of the day, as proven in Kaka's case. Plus, you might be the World's richest club, but you are only 5 points away from the relegation zone. You won't qualify for Europe (which is what the fans were saying at the start of the season) You won't win a trophy.
So yeah, you might well get the Bellamys and De Jongs, but never the Kakas and Messi's.