Right from time, the norm has always been bitcoin before others and it has always been Bitcoin dominating over others. If bitcoins could take over 50% dominance, which today, it's above 60%, it means that it is more valued and that others are just mere subordinates to it, which is why they are called altcoins.
It is undeniable that Bitcoin is the main target for investment. Moreover, Bitcoin also first appeared before the birth of Altcoin, and BTC also has a limited supply so that people have great potential in making satisfactory profits.
As long as we don't support the btc forks, bitcoin will be more successful due to its limited supply, and since it's the oldest coin in the market if I am not mistaken, we can expect that more and more bitcoins will be lost in circulation over time and that would make the value to rise even more as the demand will surely increase more as well.
Bitcoin is the main currency... altcoins are alternative currency, so you are right, without bitcoin there'll be no altcoins.