neither of these two are considered "U-turn". they both are still on the same path as they were before with the same mentality about bitcoin.
- JP Morgan is threatened by bitcoin because as bitcoin grows, their power shrinks and they can continue their corrupted ways and their revenue is going to be cut short. the only reason why they created their own cryptocurrency is because they are afraid of bitcoin and don't want to be fallen behind.
- Buffet doesn't understand or wants to understand bitcoin, he is old school and believes that only businesses and factories that produce something physical or give some sort of service are worth investing in. which is why he invested in the companies not in bitcoin itself.
It's an obvious fact that the guys are very scared of been irrelevant anymore in the financial market, thus would do anything to give negative comments/reviews about Bitcoin based on their selfish interest.
I'm very confidence that Bitcoin will put all naysayers to shame and stand out to fulfill it's purpose - Financial Freedom.