It is interesting to note that the applications that will help us survive in space and on hostile (in terms of environment) worlds can also be put to use in our oceans.

But I agree with you, and with Musk and Hawking; one of our higher priorities should be to spread ourselves throughout the solar system, and to prepare for the next step into the galaxy.

One other thing we should be aware of in terms of dangers to our species survival; humans have a tendency to breed beyond our ability to support ourselves. This amplifies the dangers you spoke of.