Steemit is ripping my posts off, Posts are worth less & less.

This is a common problem which I cannot accept.
The fact that you wake up and find out that your posts written with your hand, blood and brain are worth less and less and less.
I documented this procedure over the last days because its important to me and because I wanted to know how much my posts are worth at the end.

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I wrote 2 posts recently called: 'Too many Posts...' and 'We were murders for ...' and both got attention by @jerrybanfield, a whale with the vision to help undervalued posts in his series called Upvotable.

My most recent post called 'We were Murderers for 90% of...' is now tagged as Post W.
The post before is called 'Too many posts - Less UPvotes...' is now tagged as Post T.

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The first day which was Tue, 25 2017 at 5:28pm Post W was worth $7.75 as noted on my digital whiteboard called Ziteboard on the playstore avaible. Post T was worth $8.45 as noted....

On the next day however things started to change :
On 02:58am Wed.
Post W was worth $7.64
Post T was worth $8.78
An increase of $0.22 since last price check.

On Wed. 03:20pm
Post W was worth $7.62
Post T was worth $8.75
A Decrease of $0.05
Too speed things up I'll make the sentence shorter.

Thursday 01:20am
Post W was worth $7.31
Post T was worth $8.39
Decrease of $0.67 over the last check and total decrease of $0.72

My last check was today (depending on timezone)
Post W is worth $6.11
Post T is worth $7.05
Decrease of $2.54 from last check and a total decrease of $3.04

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Can someone explain where and why most posts lost so much over a few days? How can two posts lose a total value of 3 Dollars? Dispite the price and downvote (zero) there is one idea that big whale votes are causing the lost. If a lot of whales vote then the money has to come from somewhere. That's my idea and I wait for someone to teach me the coreect answer.