Those Steem 'whales' are just people like you and me. I suppose they mostly they care for two things: a) making some profit (as almost everyone on Steem network, right?); and b) making sure Steem becomes popular, as that is in their best interest. Both goals can be achieved by upvoting the content which could become popular. So they do that :)
Few of them use bots, because they do not have enough time to read everything, and actually prefer to spend their time programming those bots :) But some really read stuff and vote accordingly. This is up to their personal tastes and abilities.
It is natural there will be many people who are not happy because they got not enough votes. But thats the life, thats the humanity. If you ask me, I would honestly say I do not believe really good things could become popular, and I personally do not like 'popularity' to be used for valuing content. 'Popular' does not equal 'good' or 'quality'. Many people believe it is, but it is definitely not. Steem is not the only platform making this assumption; actually every platform nowadays is based on this, and that is genuinely wrong. As a result the most valuable things will never be noticed, as they are often hard to perceive and to understand.
Anyway, enough complaining :)
Cheers!