What do you think, really affect the cost of bitcoin without buying it.?
I don't know what are these rumors you are referring to, but the announcements regarding bitcoin futures have been pretty clear and coming from CME group directly. there was nothing to doubt and become rumor.
and as for the effects, I believe the current rally is mostly because of that news. and when the price rise begins, everyone else joins in. it is not just because they are adding a market and that market is attracting investors, but instead it is the news about them adding the market which is putting bitcoin on the radar of many investors who now are seeing bitcoin as a valuable option to invest in. and as the demand increases the FOMO buyers start joining in and price rise becomes fast. probably even reaching $12k pretty soon.