Bitcoin of course being the "safest" crypto, since it's so ubiquitous, and because no one person really controls it. Not so even for Ethereum, even though it's the next best thing to "diversify" into (read: speculate on) in regards to crypto.
I think the casual reader needs to know that distinction, lest they get a nasty surprise such as—oh IDK—Bitcoin dumping 80%. Because if it does, then all the other cryptos will most likely dump 95% or more. Or worse, go to zero like the "safe bet" Luna. And so much for "diversification!"
It's like that due how all crypto coins are high risk assets that are all highly correlated to Bitcoin. And so the correct wording for buying other cryptos should never be "diversification" but speculation.