I personally think you may be describing assumptions as if they are guarantees. Once the incentive model changes, user behavior will change as well.
Increasing curation rewards is certainly a possibility and it has been discussed. It may be part of a solution to improve things. It also isn't a perfect solution as many investors aren't spending their day curation content. It also means more of the rewards pool goes to those who already have a huge stake (curation rewards are negligible for small accounts, but significant for larger ones). That might further increase the divide between the haves and have nots which comes with its own problems.
I don't see why investors need to spend time reading content in order for the cryptocurrency token they invested in to go up in value and increase their holdings. If anything, the social media side of Steemit may confuse investors away from understanding the true value of STEEM, as I explained here.
there's only one reason to invest in anything, and that is more money. people want to maximize their profit and minimize their work.
make it easy to profit, more investors come in
start attacking people who self-vote and they will cash out
the only solution is to make curating benefits more than self voting, I can only think of one way to achieve it. is there any other way?