you know why our post SBD value is go down day by day
That's because Steem Dollar and @Steem are 
Our SBD is loosing his value cause the Steem and Steem Dollar is losing value
yes
this is happening because our vote depends on the 
if the publication have more than 7 days is irreversible there is nothing to do with the devaluation One Japanese man, selled 400 million Dollars in Bitcoin at Tuesday
and bitcoin d-valuated and this also affected Steem
I advise you not to pay for promotion or voting and sell your SBD until it grow up
because before the 7 days pass you will lose your investment.
everyone is suffering now, but the market will valurize again
but it can take some months or some weeks visit at this link for more information
https://www.coingecko.com/en/price_charts/steem-dollars/usd#panel