bitcoin is a currency that is in its initial steps of being mass adopted as a currency! and that makes it the number 1 coin. and for that reason ethereum won't even come 10% close to bitcoin's position ever. not in a million years.
but i know that none of the ethereum shills are even remotely interested in real world usage and only are interested in market cap!
so here is that calculation for you:
bitcoin market cap is currently about $71,118,159,376
and ethereum market cap is currently about $28,814,068,277
ethereum can easily release 138,337,819 new ether tokens and with the same price reach the bitcoin's market cap like what they did with the 72 million premined ETH. if they don't change the supply, with the current rate it will take about 90 years to reach bitcoin's market cap.
also if we consider price then eth only needs to be worth $755.97 to reach bitcoin's market cap.
that is how fake the market cap is. you can easily manipulate it with your fake supply (premined) and have a bigger market cap than bitcoin with a pathetically low price.