How did cardiology become so powerful?

It’s crazy how powerful cardiology has become as a specialty. They’ve cornered the market in a way no other medical specialty (intervention, imaging etc) has and far more financially motivated as a specialty than the others. Of course others are also but it just feels like the specialty societies are incredibly aggressive at taking as much of the market as possible.

Reading cardiac CTs…? You don’t see pulmonologists read ct chests or neurologists reading mri brains.

Anyone know how they did this? Has the specialty always been like this?