of course the price matters. it matters for the people who bought their coins. if the price is stable more people are willing to convert their savings into bitcoin.
Not just for those people who bought coins but for all the people who are using bitcoins and having some trades with it. The price is really a matter of importance in bitcoin and this is why we are loving the way it is making itself well known. And as of now, the price did reach ATH for this year and many of people surely encouraged to use it.
when you only consider bitcoin to be purely for investment then the price becomes important to you, there is no argument there.
but bitcoin is not just investment, it is also a currency that we can use to buy things with. in that case the only thing that matters is bitcoin itself, its security and as far as price is concerned the stability of it is more favorable than a volatile price when you are spending it.