Nobody can figure this out, because you do not know how much bitcoin price will be during those ten years of your bitcoin accumulation timeline. You should know that bitcoin is volatile in nature and since you will be using DCA to accumulate weekly, you cannot get the same quantity of bitcoin for $100 whenever you buy weekly. This is the reason why I feel no one can figure out how much that you can use to invest into bitcoin for ten years before withdrawal through sustainable income.
However, the amount of money that you will use to invest weekly depends on the amount of your discretionary income and nothing more. That's why when accumulating bitcoin, you don't use a timeline for your goal but rather, you need to have a bitcoin target which you plan to accumulate. So that, whatever timeline that you use to reach your bitcoin target wouldn't be important. Personally, I feel that ten years cannot be enough for a pleb that is investing $100 per week because in 10 years time he will be having invested $52,000 which is not up to 1btc.
For you to reach over accumulation so that you can start using a sustainable withdrawal to tap from your bitcoin, that person will need more than 1btc and it depends on the age of that person. Someone in his late 60s and early 70s will spend less funds compared to someone in his late 40s and early 50s because he might only carter for himself and his wife. But someone in his early 50s still have children to take care of.
I also agree that setting a BTC accumulation target is more realistic than hoping for a particular date. With Bitcoin’s volatility, long term plans are difficult, so sticking to a budget DCA to Bitcoin and DCA to other assets you may have and adjusting as life events unfold is a better approach.
No, I think otherwise though, I don't think the best way to set a clear goal of your Bitcoin accumulation is by setting an accumulation target with numbers, to me if you do it that way, you are limiting yourself to an extent, but if you are setting an accumulation target for like 10 years or more and you are as consistent as expected, their is a higher probability that you may even accumulate more than you can ever imagined, because by doing so even if you have over accumulated, you would not stop till you have gotten to the duration of time targeted, but if you are setting a number of Bitcoin as your target, you are practically limiting yourself because if you achieved it faster than expected, you might be discouraged to accumulate even more unlike someone that is using timeframe to accumulate.
Setting numbers of Bitcoin as your target might discourage you to go further in so many ways, just imagine that you won a contract and the discretionary income left is enough to buy the exact numbers of Bitcoin that you targeted, don't you know that you will feel too relax and the will to accumulate more will struggle to be there, so using a timeframe is the best in my own opinion.
That is a different perspective that is also interesting and valid. Having a deadline instead of a predetermined BTC goal could work to focus you more. That helps to build discipline but is particularly helpful when motivation wanes. At worst, a goal based on a number could lead to stasis after reaching it, but a time based goal tends to be more energizing. Ultimately, it is an individual decision based on psychology. Some people work best with targets and others with deadlines. What is essential is in both cases is steady effort and engagement, no matter which way is preferred.