If whales are wrong, the value of Steem declines. Whales own the most Steem. Hence whales lose more if they are wrong.
No, if they understand the system, people are not incentivized to vote after whales. Rather, they are incentivized to vote BEFORE them. It's the early voters who get most of the curation rewards on a given post. Many people make this mistake.
What empirical evidence do you have that pandering to whales is resulting in different, and presumably inferior, content being posted here compared to other social media sites? From what I can tell, it's mostly the same stuff (though perhaps far more crypto focused)--travel blogging, philosophical and political debates, pretty girls (though less than on, say, Reddit), persuasive writing, fiction, photos, etc. There's no evidence that I can see that Steemit content is materially different than, and certainly not lessor than, content on other platforms.
I do share your concerns to some degree. For instance, I've invited several notable authors to join Steemit who write primarily for the LGBT community. To date their posts here have gotten little to no attention. But, I'm convinced that will change over time, both because the currency will be more widely distributed, and because whales are not stupid--ultimately they will support posts that don't interest them personally simply because it's in their economic interests to do so. For instance, I have little personal interest in reading LGBT oriented material (its just not my thing, not that there's anything wrong with that), but I consciously invited two different LGBT-focused authors to join and post here, and I've made every effort to up vote and promote them whenever I can.
How does steem "lose value" if a whale upvotes a bad post?