although many altcoins have a better potential than bitcoin but they cannot guarantee that they can continue to survive in the future and bitcoin will remain firm on top of being one of the best digital coins of all time.
This. Not just because they have a lot of potential doesn't mean that they can surpass bitcoin. Just to remind everyone, altcoins are made from shadow of bitcoin since they see it a successful one and they're dreaming to have somerhing that can follow what bitcoin has reached.
And I think bitcoin is a benchmark for all cryptocurrency.
Yes it is. Just see how altcoins' value depends on bitcoin movement.