The price is one of the indicator of bitcoin's success. What you're saying is totally right, bitcoin will be continued to be used even if it was at $1, but if something goes down from $70k to $1 then it also means that somehow it has failed. There will be people who will keep using bitcoin but forget mass adoption at that point.
Then of course are also people who took the risk to buy bitcoin I can totally understand if they want to get some profit, nothing wrong with that.
Yes of course, we believe in Bitcoin, even though it has low Value like you said people will still use it.The price of Bitcoin is showing market conditions and the main key in Cryptocurrency (this is my opinion), isn't Altcoin following the movement of Bitcoin and from here it is clear that the price of Bitcoin is the most important thing in the course of Cryptocurrency.
Apart from that, the price of Bitcoin is of course very important for investors, as well as in terms of long-term investment profits, and several countries use Bitcoin as a currency for transactions, and as a currency, of course, price is the most important thing to pay attention to.
The price of Bitcoin is a top priority, and this includes everything in Cryptocurrency.