Edit: granted, I didn't mention that it's typically great white, tiger and bulls that are life threatening among sharks. So it isn't really a billion versus 50k. Regardless, there aren't really that many fatalities by sharks per year.
Next to that Orcas frequently interact with humans, more than sharks. For instance as this article describes, they are quite active in the tiny mediterranean sea. Which some human even swim across (60 attempts per year).
Also they live close to the surface, they need to breath every 5-15 minutes. And just as sharks they enjoy Sea Lions, which sharks often confuse with humans.
Also they don't often confuse Sea Lions for humans, but it's still a good explanation for the few attacks that do occur. It's actually impressive how good they are at recognizing their prey.
Orcas are savage, incredibly strong, smart, and capable pack hunters. Absolute apex predator of the sea and sharks don't stand a chance.
To be clear, shark livers are so big because they have an extra job ours don't.
Sharks are a group of taxonomical orders. Orcas are a species.
You wouldn't want to swim with them anyway, for the same reason you wouldn't want to run with a herd of stampeding cows.
But it doesn't matter at all; the difference between the taxonomic level of "sharks" and the taxonomic level of "orcas" is unimaginably large regardless of what you want to call the levels.