the question is already answered hundreds of time by the market itself and the answer can be found by simply looking at the history (that is charts) and it has nothing to do with market cap since that is just an arbitrary number that can easily be manipulated by altcoins.
in short:
there is nothing that can compete with altcoins in short term since they are garbage pump and dumps that can be pumped thousands of percentage in a short time like half a day! there is literary no asset in the whole world that can be pumped like that in such a short time. but at the same time it is a pump so there will be a dump right after it.
but when it comes to long term, since bitcoin is the only cryptocurrency with actual utilities and real adoption in real world not just on exchanges, it has the long term potential and will continue growing no matter what happens in short term. in other words when bitcoin price rises it won't come down.