I don't know if the DCA method can be calculated in terms of the Bitcoin quantity because what I do know is that it is based on dollar amount that is why it is called dollar-cost averaging. If an investor decides to buy a fixed quantity of Bitcoin per time irrespective of price fluctuations, that is possible and achievable as it may be that he would have set a target to achieve in terms of Bitcoin quantity. For instance, someone can set a target of owning 1BTC before his 20th birthday and may decide to be accumulating 0.01BTC weekly or monthly as the case may be. As expected, he would have made adequate financial preparations for this, bearing in mind that while following his plans he will also pay his bills and also set up some reserve funds. I do not see anything wrong with setting such personal targets neither does it mean that he would not have factored in price fluctuations in his planning.
I look forward to seeing what others will have to say about such plans, if it qualifies as DCA or something similar to it. I'm with my pen and my note, time to learn something new.
For me I really don't think an investor can be able to buy a fixed quantity of Bitcoin within a stipulated time interval reason being that the price of Bitcoin might keep soaring higher thereby he can't afford buying same quantity of Bitcoin as the previous one he bought while the price was lesser and moreover, just like your illustration about if a investor wants to achieve 1BTC on his 20th birthday and let's assume that the birthday would be in three years time and his DCA every week is like $1000 and from his speculation of the price of Bitcoin in that three years is like $150,000 and let's say in that 3 years the price of Bitcoin now reached $200,000 so definitely his DCA in that three years will amount $156,000 so you can see that he didn't meet up his targets of owning that 1 BTC on his birthday after his speculation 3 years back.
There is a saying that "the end justify the means", so when the end is known, there will always be means of actualizing it. You seems to sound with the tone that everyone investing in Bitcoin is so poor that they cannot afford to buy Bitcoin if the price makes x2 of the currency price. This is a wrong mindset because there are a lot of rich people investing in Bitcoin and such people can set their plans based on the quantity of Bitcoin they want to have accumulated at a certain time in the future. Some people can even set the target of buying 1BTC per year as long as they live, to save the money for their children. These are possibilities that we cannot ignored thinking that everyone investing in Bitcoin is broke. You must understand that our purposes of investing in Bitcoin differs.
While some people are buying and holding Bitcoin as an escape from poverty, some are pushing some of their funds into Bitcoin as a hedge for their other businesses. Some are actually saving their retirement benefits in Bitcoin. We must appreciate our peculiarities as that itself is the beauty of life. What matter most is being able to invest in such a way that it will not give you pressures or discomfort.
Regardless of the fact that we're optimistic about the future but however, the future is not known as all we are doing is just taking the risk and expecting to join the billionaires if things goes in our direction, actually I don't have that mindset that people who are investing in Bitcoin are poor, moreover most of the highest investors are people that are wealthy but what i was only trying to clarify is that as time goes on that's how the price of Bitcoin keeps skyrocketing thereby anyone using the DCA and making speculations about having a certain quantity of Bitcoin at a particular time in the future may not really achieve that though making speculations are good because it helps to boost ones confidence spirit that you are almost at the verge of meeting up your desired accumulating amount but sometimes when we give time with which our investments would be matured enough it might make us to stop buying when we approach that target we had that's why I said it is better to keep buying and hodling regardless of if you've met your target or not.
Buying and hodling doesn't only stand as poverty alleviation for the poor people in the society but for all and sundry who wishes to venture into Bitcoin investment in other to accumulate the asset in their portfolio so that it can stand as a future income generation strategy for them maybe when they're are not too strong to work again and continue DCA.