This piece literally sums up the whole idea of investing wisely which is by investing an amount of money you can afford to lose. Investing with a sense of moderation. We need not put all eggs in one basket and by way of this in figuring out our respective level of balance to avoid reckage is by diversifying our investment to other physical assets within our reach that we know can be profitable in the long run.
I am not suggesting that there is any need to diversify into other assets besides bitcoin and cash, especially for newbies who might be in relatively early stages of building their bitcoin investment. It can take 5-10 years or more just to build up a bitcoin investment size (at least the amount that you had invested into bitcoin) to be equal to 1 year of your expenses.
I think @letteredhub did not understand the point you were trying to make and besides our most important goal is to be able to have a lot of Bitcoin available on our portfolio so diversification should not come to play at that moment , so actually, improper planning of diversification can even lead to inability to achieve anything at the end.
What @letteredhub is missing is that it may likely take somebody or a beginner who just started investing on Bitcoin using DCA strategy possibly over 11years to have a good Bitcoin stash on there portfolio and sometimes they may not even have enough Bitcoin after that number of years based on the amount they use on weekly basis, so perhaps he cannot advise such person to leave accumulating Bitcoin and diversify into another investment because it doesn't sound nice, so actually if there should be a time of diversification it should be when the person have achieved his Bitcoin goal before they can talk about any other thing.