What's wrong with high rewards?
In my opinion too high rewards for self-voting, as well as extremely high rewards for trending posts are counterproductive.
The convergent linear rewards curve (which I had recommended years ago!) decreases the rewards for self-voting, allows high posting rewards but prevents extremely high posting rewards - and thus is the best solution.
You are totally right under the condition, selfvoting remains. But the government should scratch this destructive possibility. Selfvoting drains the pool and destroys the social reputation of any selfvoter. There is no notorios selfvoter respected by communities except by pool draining whale gangs.
Here we go!!