There are always going to be people who do things for selfish reasons. It is best not to get too hung up on what those people do. If the majority of us focus on using our stake for the betterment of the platform, then I think we'll be fine.
I think you are too optimistic here. People will do whatever makes sense for themselves first and foremost, and consider the long term effects and effect on others second - as long as it does not negatively impact them to do so. There is precedent of this viewpoint in the whitepaper, specifically in the discussion of the Prisoners Dilemma. We need a further change to rebalance this or HF 19 has partially failed.
However it's not all about financial incentives, there is also the social component and it's there that I would feel optimistic, though not as much you 😜