In a negative mood?
What you say is true though it is much easier to put humans in outer space than it is the deep sea at least in small numbers though we could discover things that could be of much greater benefit in the short term by exploring our oceans and if we used unmanned submersibles it would be cheaper than space.Of course by dong what we do I'd bet that we are causing damage (the "pools" of plastic and other trash in each ocean the one in the Pacific is the size of the CONUS I think or is it the size of Texas.) and we dont even know what we are effecting.And you are thinking of exploitation I assume which of course that is gong to happen so I suppose I can agree with you better that those types do not know what is down there as they wield all the power.
In the grand scheme of things your last bit is true as well I suppose but then again that is how it works out something will replace us just as we replaced something else once the usefulness is gone nature will take its course and that we will not be able to stop.