Ethereum is giving bitcoin a hard chase as it is gradually dropping the market value of BTC. This is expected to continue as many investors are flooding to ethereum.
It looks like you are a newcomer, right? Bitcoin has ever placed at the second position a few years ago when ethereum ever surpassed bitcoin in term of marketcapitalization. This is not something new in crypto because bitcoin can try to get back its dominance again in term of coinmarketcap easily. Bitcoin already increased a lot and it takes the time until the next pump will happen.
bitcoin becomes a rare commodity from day to the another day.
The flippening can happen anytime to get the domination in crypto again. that's easy for bitcoin to do that.