weirdly they feel a lot more sensible than actual whales, to me.
Whale sharks are effectively just an oversized non-bottom-feeding version of those fish you put in an aquarium, it's not strange for a fish to evolve like that.
But actual whales? Somehow a creature looking like a boar turned into pseudo-fishes that spend all their time under water while still having to breathe air, and became so ludicrously large that the smallest ones are human-sized. wtf