Nothing has been 'proven' because what happens under one set of economic rules and balances are very different from another.

It could very easily work out exactly the opposite of what you are claiming because the trolls are willing to pay the high price for their abusive downvotes, but others are not willing to pay that price for altrustic annd beneficial downvotes (which increase rewards to legitimate users and contributors by pushing them back from the milkers). So by keeping the cost of downvotes high, as it is now, you end up with only abusive downvotes and toxicity, but with cheaper downvotes you have non-trolls willing to use them for good.