Without btc alt coins would no longer exist, and all of tokens when converted to real currency undergo to btc. This makes btc become popular and continually increase its value. There's no doubt btc is the most strongest digital currency ever made by mankind:)
And altcoin would never going to exist in the first place if there is no bitcoin, to be honest. Altcoin is short term for Alternative coin, meaning it is not thst major compare to bitcoin. Bitcoin is a KING, you could tell it by just its price which dominates all of the coins prices. Bitcoin is the superior of all the Altcoins here in this cryptocurrency world.