People are not ruining anything. They are only using Steemit in the best way possible in their own best interests. This is called capitalism and it's the fundamental model upon which Steemit is built. Perhaps in a hard fork there will be considerations for other models. But right now, Steemit is capitalistic.

Hence the need for curation rewards. Curations are strictly a capitalistic concept in which greed for the curation is supposed to drive people to upvote "quality." Unfortunately, upvoting your own post and even more so your own comment provides a much higher profit than a curation. So while greed is a motivating factor, and curation rewards are less than author rewards, no one has the monetary incentive to vote other's content, except maybe whales. So that leaves the quality of Steemit in the hands of an elite few. Just like anything else run under a capitalistic model.