Never have all your eggs in one basket. So with this reference, I can say you should prefer to keep your money invested in some solid projects including Bitcoin. Ethereum is a safe choice.
Never put your eggs is one basket is correct, but i don't think that idea should apply to diversifying into BTC and Altcoins, it is more logical to put those 'eggs' into other investments that aren't intrinsic to crypto, investments like Real Estate, Gold, etc.
Altcoins are 'wild' and if you haven't invested in them before, i may advice you to forget about that option. There are seasoned altcoin investors,
who know how to sell fast when it comes to the point of dumping, if you buy with them when the alts pump and help them pump the price the more, when it begins to dump, they will dump or sell on you before you know what's happening, leaving you with worthless coins.
Some big businessmen and traders say that sometimes you have to take risks to win and this can be true to a certain extent and in certain circumstances, but with digital currencies I think we can see it differently... when we talk about risk, we can focus on this issue, as the availability to risk investing in these, the problem comes when you have to decide which of them, since the arrival of bitcoin many other versions of this called Alcoins have come out that have tried to improve the characteristics of the original but many of these projects have failed, so if we take this into account, it could be said that for many the best option is bitcoin, and it is with the only currency, which personally I would dare to choose for this bullish cycle and for any other time...
Never put your eggs is one basket is correct, but i don't think that idea should apply to diversifying into BTC and Altcoins, it is more logical to put those 'eggs' into other investments that aren't intrinsic to crypto, investments like Real Estate, Gold, etc.
Now if my income is good enough, I would choose to do what you indicate, because I agree that it is better to play it safe where you put your capital, real estate and gold...especially gold...they are options that can provide security, I would definitely go these roads.