Bitcoin is the leader of cryptocurrency, and billion-dollar corporations prefer to hold Bitcoin as a store of value. Because of its first-mover advantage and brand recognition, Bitcoin can be considered safer than Ether. But keep in mind, all cryptos historically are volatile.
Cornerstone Macro analysts wrote to their clients: “Given that there are diversification opportunities among digital coins themselves, we should consider a small basket of them, rather than just Bitcoin alone, when we assess whether some allocation to crypto assets can reduce portfolio volatility alongside traditional assets.”
When the price of BTC falls, then all other coins lose their value. If you are trading on the growth or fall, it makes sense to distribute capital.