To me, I think the essence of all this which I think is best, is don't do more than yourself, invest with what you can do away with for a very long period of time, that's why the DCA accumulating strategy is the best because you will be accumulating Bitcoin through the DCA method either weekly or monthly according to your financial strength, and as long as you have a source of income to be funding the DCA accumulating strategy either weekly or monthly you wouldn't be compelled in tempering with your investment just because of some financial needs.
But if you are doing more than yourself, by investing more money, and part of the money that would have cover up for your well-being, at some point, when having a serious financial needs, and your emergency funds are not enough, you will be force to temper with your investment, before you know it, that will be the beginning of the end for that investment, because that will be how you will be eating it bit by bit till it runs out, so it's very important to invest according to your level or I say it like don't do more than yourself, just cut your coat according to your size when DCAing , then you are good to go.
Everyone needs to tailor his investment accordingly to his financial status and also the amount that would be comfort with, two persons might be earning equal amount and having equal financial stability but would be comfortable with different allocation, Mr A might be okay with an aggressive 25% weekly and Mr B might be okay with 10% weekly despite been at same level with Mr A and this might be due to each of them having different risk tolerance relating to investing in bitcoin or having all their value in only one asset.
You made a very good and interesting point but I want to point out one aspect of your statement that does not quite sit well with me. That is the aspect of using "risk tolerance" as a factor for investment. In the example you gave, it should not be ability to bear risk that should determine what percentage each of them will allocate to Bitcoin, rather it should be dependent on their individual needs. Using risk appetite as basis for determining the amount to allocate to Bitcoin might seem like Bitcoin is all about risk, a way of amplifying the risk of Bitcoin. So, needs is a better factor to consider and for this case, Mr A might have needs that requires up to 50% of his income while Mr B might have needs that requires just 30% of his income. Under these two scenarios, Mr B will have more leverage to allocate higher amount into Bitcoin than Mr A.
Meanwhile, when I said needs, I am referring to basic needs and any other thing of importance that cannot wait. These are the factors that can force an investor to sell his Bitcoin. Besides these needs, the other major consideration should be emergency funds which covers unforeseen circumstances.
Those are mere hypothetical to explain the mental situation of two different persons with equal needs and every other necessities in place. Mr A feels comfortable and okay with an aggressive 25% allocation to bitcoin and that doesn't seem to bother him or give him a sence of over allocation to bitcoin whereas Mr B feels okay with his 10% whimpy investment despite knowing he could allocate more to bitcoin.
I made this hypothetical to picture that there is a risk or possibility that your investment in bitcoin might not do well or even go to zero and both persons knows and recognize this fact, this brings us to a point that everyone should invest money he won't miss cause its also possible for your investment not to do well, Mr B might before conscious of this and decides to have more cash than investing in bitcoin and Mr A choses otherwise.