the market cap number is meaningless
i can create an altcoin of 1 trillion coins and sell just a single coin for $5. giving the alt a market cap of $5trillion
this does not mean i have majority market because my cap surpasses bitcoin by more than 10x
by this i mean it doesnt mean my explanation make bitcoin any more or less important. it means making claims by using market cap are meaningless
EG
if i stood at a road junction and slapped on pro trump bumper stickers to random cars. does that mean suddenly there are now more trump supporters simply because a poll counts bumper stickers?
I agree as marketcap statistics are approximate not actual, as it may vary by volume increase or decrease. But still Bitcoin is prime/master coin among crypto market. Increasing dominance of BTC surely kick out dump altcoins, but at the same time if dominance of BTC shows lower numbers, it means that altcoins are creating share in whole coinmarketcap, which indirectly increase value of BTC.