I don’t really think there’s much money going into building anything that could take humans to the depths of the ocean. The general interest isn’t there, and it’s not as glamorous as space. Besides, our future lies in spreading among the stars, because ours will consume the Earth. Hiding in habitats a few miles below the surface of the ocean won’t save us.
Yes, you’re right, it’s not as glamourous, and that’s why there are a thousand sci-fi stories in space for every one about some guys going to the depths of the ocean. Still, it is much more practical, and when you are dealing with science and not science fiction, practicality is pretty important.
Also, colonizing/exploiting the inhospitable parts of the Earth, and doing the same thing in space aren’t mutually exclusive. I think they would be completely mutually beneficial. If we can conquer the hostile environments on Earth, we can only increase our ability to do the same elsewhere. Just like building biospheres in the desert are a cheaper way to learn to build them in space.