It also grows over time as newly created steem is redistributed to SP holders. Refresh the page on a high steem holder and *watch it grow* :)

Liquid Steem (Stm) is sell-able immediately and gains no interest payments, Steem Power takes 2 years = 104 weeks to power down to STM. SBD Steem dollars are sellable immediately and so is Steem Liquid .

Steem Power ( SP )and Steem Dollars ( SBD ) both gain ten percent interest per year paid to you. This interest is paid each month on your acct balance of SP and SBD.

Liquid Steem gets no money as interest payments, so people should consider that factor since every day new steem is mined by the miners as cryptocurrency.

So regularly your entire Steemit account is bleeding away in value, this loss of account value affects everyone Whales, Dolphins and Minnows . . . 

For example many years ago a man bought BTC then later he was filthy rich; I include the story link.

 https://www.theguardian.com/technology/2015/dec/09/bitcoin-forgotten-currency-norway-oslo-home

So no matter how rich a Whale might be in 2016 they must keep using the Steemit platform or their cryptocurrency will just dissolve over time . . .

Plus every vote a Whale makes makes so Minnow or Dolphin more powerful, so over time the most talented people who consistently use the platform will become the most rewarded : )

Unless of course I am mis-understanding Steemit platform mechanics ; )

Yes that is correct.  Power down happens weekly in parts over 104 weeks.