there is a lot of demand currently and that drives up the price. When demand is higher than the supply of something the price goes up, in BTC's case the price is going up because many new participants in the market want to buy BTC, they are hearing the news about BTC being integrated as a future in the CME group, and they are sure that this will drive institutional investors to invest in BTC, so everyone is buying now BTC in anticipation that the price will continue to go up. It has already performed very good within this year, going from around 800 to over 8k, which is kinda insane if you think of it. Everyone is making money at the moment which makes you kinda wonder whether we are in a bubble or whether this entire thing is sustainable.