In our field if you can make long term predictions then you wouldn't call it volatile really, because you can predict what it is going to do exactly from a couple to a year up front sometimes even years up front. It only looks volatile to people who aren't sure what they are doing. (Yes technically by literal definition it is and has been but who cares about technicalities). You could entirely very safely predict that when regulations would go through BTC will go into chaos while ETH would draw power from it just because why they are both used. (BTC would only stand if they make it something more).
Anyone can make his or her wild educated guess in this market. And probably what you are saying is that we should look at the bigger picture if you want to make a prediction so that volatility will be a small factor on it. And most likely why DCA method is also the best as it doesn't matter was it the price as you buy in averages. It could be volatile for those short day traders or traders by definition, but to make money they will have to make volatility it's friend. As for ETH, not sure about it, it's totally different in terms of usage or even adoption and so I don't think that there will be comparison.