The game started in England. They have always had huge numbers of players compared to just about everybody else. The RFU had the finances to own Twickenham, which sells out more often than not. Rivers of gold.
The question should be, with all their natural advantages, why are they not perennial winners of everything?
After beating the Springbok and losing to the AB's by a contraversial TMO decision, his team will put the sword to Japan & also (probably) the Wallabies, then he'll probably be able to wrap up a deal with England Rugby for after the RWC, assuming that's what he wants. And money does have a very compelling language.