I think there is another option. While yes it may be considered an investment a savvy tech giant like Bill Gates could buy steem because he wants to show support for the platform. He may solely enjoy reading content and not care much if the return does anything, but will be able to help others in a way that before now was not really possible. By buying a large amount of steem it will create a demand and drive the price up (I believe).
Yes this is not likely the case for most of us who are using the platform, but I would not be surprised to see donations come in some sort of way.
I like the system being that the more money you have invested the more voting power you have. A whale cannot simply pull all their money out after wrecking havok amidst this ocean. In fact apart from finding it amusing, I can't imagine why a whale would want to waste money in this way. Investing money to me is the belief in long term gains like you said.
I like the system this way and would not wish to change it.