"who will buy ?"
People who want the token, same as with every other good/commodity/crypto/etc.
"And who would invest in a new account when 1 blurt is 5$"
Reminds me of "who would invest in gold when it is $1000 per ounce?" We heard that one for years. Now gold is $2000 per ounce and continues to be bought/sold all the time.
"blurt is a coin that can be printed by the rewards pool forever.. blurt will stay down forever"
A majority of tokens out there (thousands) are the same. Will they all go to zero? If so, you could make a lot of money shorting them all! Reality though is that Blurt (and other tokens without a set limit) does not go toward zero, but fluctuate up and down over time. There have been bull and bear markets for Steem, Hive, Blurt, and thousands of others. Your prediction does not make sense and doesn't reflect reality.
"That is if external forces do not manipulate the market. But we all know external forces always manipulate everything ."
In the case of BLURT, how would external forces manipulate its price?
"And many witness on blurt will sell his soul to Klaus for personal profit anytime ."
If that was possible, how many votes do you think witnesses that destroy the platform and collapse the token price would get? There are safeguards against out of control witnesses. I can unvote someone in 5 seconds, as can you.
"where will the increase in value come from ?"
This demonstrates a fundamental lack of understanding of basic economic principles. You could ask the same question about anything. Also, we're talking about price, not value.