I've noticed the whales using their slider so they can upvote more comments. Most of the whales realize that the only way Steemit works in the long run is to curate. Don't forget that these whales are sitting on hundreds of thousands in Steem Power. The only way that pays off is to expand Steemit by curating. When they curate, it gets minnows excited. Minnows tell others who become minnows and that increases the value of the blockchain and THAT makes the whales money...way more potential of larger payouts than upvoting themselves all day long.
I have noticed whales and dolphins simply splitting up their upvotes into smaller increments so they can use the upvote more often. This is just what I have noticed. YMMV.
My humble advice is to find something you love and create content around it. Do the daily grind and produce. This is what will get people to upvote you. And curate minnows...reward the minnows who comment and like your content. Those minnows will be dolphins one day.
RE: Why It Doesnt Make Sense To Upvote...