What is the point of measuring Ether's ROI in terms of BTC? Why not just measure in terms of fiat, or gold? Why choose a volatile BTC?
Because a lot of people plan to invest in BTC. And there is an opportunity cost.
If Ether underperformed BTC, it's make no economic sense to convert BTC into Ether.
Ok. I view that as investing
with/using BTC, not
in BTC. BTC is just a tool to invest in.
The fact is that neither you or i know the future. BTC may be a better investment, but who knows? You may also invest in some other project which will outperform both btc and ether. Then following that logic it makes no economic sense to invest in both Ethereum and BTC.