the article from coindesk clearly says " he said that the cryptocurrency would "not survive" back in November 2015 when the price was fluctuating around the $400 level."
"Dimon later added that the cryptocurrency "will blow up," according to CNBC. It was also during that appearance that said that he would terminate any trader that he found to be trading bitcoin for being "stupid."" from coindesk article.
He pointed cryptocurrency not just bitcoin. Then my assertion is why he created his own version of crypto.. it is self denial.
That's why the CEO of JP Morgan publicly state that Cryptocurrencies. It's a form marketing strategy, once all other Cryptos are demolished it's a good time for Him to release his own Cryptocurrency the one that they can control and manipulate. JP Morgan is attacking the emotions of all the investors so that the will sell all their Bitcoin, that's why it contributes to the decreasing value of it.