You are welcome, I am still very much learning as well so if any content I put up is wrong let me know.
I did decide to buy steempower as I believe steemit will continue to grow exponentially and it's uniqueness and potential will attract advertisers and investors from around the world once steemit goes to the masses..
Also the top investors/ creators generally are proud of their baby so they most likely want steemit to succeed as well, but that is just pure speculation. Them powering down also has a positive side, as power is more spread amongst the participators.

The following link explains what steem dollars do, the rewards by posting and upvoting are eventually payed back in steem dollars. Where does this money come from?
Well the higher the marketcap the more steemit can loan and distribute as steem dollars amongst steem power holders. (same as what a bank does with mortgages putting equity, they use real estate as colletoral to loan money) These steem dollars can then be transferred back into steem or powered up to steem power.

The above info I took out of the great posts below!
https://steemit.com/steem/@steemrollin/steem-where-does-the-money-come-from
https://steemit.com/steem/@bitcoiner/steemdown-com-which-whales-are-powering-down

We should really try to make a simplified version of the explanation so that everyone can understand this. It took me days to actually find out how the system works and even now there are still some mysteries to solve for me. For instance I read that one of the more important ratio's to look at before buying steem and powering up is the Mvest to usd ratio. Or MVest to steem ratio.This figure can be found on: http://steemd.com topright.

hope this helps as well. If anyone else finds info to share I would love to hear it.