you have no information on the actual maintenance cost
Correct.
I'm having doubts about this number
I did try to make it as clear as I could that I do too...
That's debatable
Well, I defined it as the maximum amount you can take out without running out of money. I agree that if instead you define it as the maximum net outflow that (with some probability close to 1) leaves your fortune increasing rather than decreasing in both long and short terms, it could be negative in times of economic stagnation.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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