A greed.
Seriously though, he deserved every cent of what he could get. He was No.1 and he was the face of the sport, de facto also the voice of the sport for several years and his fourth Olympic LJ title confirmed his position as one of the immortals of our sport.
But since you mention it, there was at least one season I recall when Carl wouldn’t lower his price and I think he may only have run two meets in Europe. So he kept to his standards and the market to theirs. Little Joe knew what he was doing and I grudgingly admired him for his tough stance. But, as I wrote, Carl’s dominance coincided (and was in some ways responsible as I’ve heard it from some promoters) for the collapse of the old circuit.
There was a time you could get a race somewhere in Europe literally every day from start of June through end of August - and you’d get paid something for it.
But then meets like Koblenz and Cologne collapsed and a host of satellite meets went under. Koblenz and Koln were great meets run by wonderful clubs … pity.
Koblenz, for those who don’t know it, is at the confluence of the Rhine and the Moselle rivers. The Red + White club hosted the meet at an elevated track overlooking the river. After the meet each year we’d all go by ferry down to the wine district and do our best… 
p