If bitcoin had a stable price at start then there were no chances to be as popular as it is now because it got popular because of investors and miners who work for profit.
It depends. If the price is not steady and going down most of the time, it hurts the miners for sure, they will have a lower value for their bitcoin and they will have lower profit. But it is different when it comes to investors, they love it when the price is moving like it is almost dropping to the bottom and immediately goes up.
I do think that when the price of bitcoin is stable, there will be lesser investors but we will be filled with users that are really after its use and not of its value.