Why do you ask as if popularity is somehow directly related to volatility. All cryptocurrencies are very volatile but only few of them are popular. There are over 1000 coins that jump and drop by 10%-50% on a regular basis, sometimes even more.
To compare the volatility in Bitcoin and Ethereum, we should place them on a chart. I’ve considered them both against the US dollar as displayed on Bitfinex. Here is the chart with D1 timeframe, which suggests that each candle represents one day:
As you can see, Ethereum is even more volatile than Bitcoin in the medium-term. Bitcoin shows a visible uptrend while Ethereum goes in sideways, though the latter is still volatile.
Let us see in the short-term (Bitcoin is Red):
On the hourly timeframe, both seem to show a similar volatility in terms of percentage. It’s true that Bitcoin can easily move a few hundreds dollars up or down, but in percentage terms they show a similar volatility, and investors are mostly interested in the percentage performance.
Now let’s discuss popularity – Bitcoin is by far the most popular cryptocoin – there is nothing you can do with it. Whenever the newcomer reads about what cryptocurrency is, he will find out – “It all started with Bitcoin. A mysterious guy or group of guys under the name of Satoshi Nakamoto…”
You can see that Bitcoin is accepted by thousands of merchants, unlike Ethereum. Also, the media attention focuses on Bitcoin – bankers and VIPs are discussing it from a favorable or critical viewpoint.
Ethereum has great value because it has features like smart contracts and the possibility to create new tokens as layers. However, Bitcoin will get the biggest portion of attention in the coming years.