We are more focused on bitcoin than ever as most of the users wants to invest into bitcoin assuming a bull run post halving but nit many are planning to invest into altcoins, I think we need to focus on altcoins as well as there are coins like Tron, ADA and all which can pump anytime and priced extremely less as of now and even if bitcoin pumps it will have positive affect on altcoins as well so I think we should invest into reputed altcoins as well.
I agree with you that we should diversify it means not just focusing on mainstream currencies such as bitcoin, but we can buy something more risky as low market cap coins can grow by 10 times and more very quickly. If you are not fond of risks, you all the same can find altcoin to yourself that has good fundamentals. For example, ADA, DOT, Matic.