Bitcoin and other coins are classified as cryptocurrency and use the same technology that is decentralized blockchain system. Today bitcoin is still the king of crypto.It is still the most popular and highest price. Bitcoin price movement also affects price fluctuation of other coins. So in that case I don't think that other coins move and develop or grow faster than bitcoin.
Yes you are right, as far as cryptocurrency is concerned there's no other coin that's growing faster than bitcoin, in fact to my own observation all AltCoins are build around bitcoin because the price of bitcoin controls the market. Secondly, there's no currency in the world that's stable in price, we should not be discouraged about the price of bitcoin to me its an opportunity to buy more because market must dance to our turn on a very good day.