Higher withdrawals increase fragility
The more cash the portfolio must release, the less room it has to survive bad years, higher inflation, or weaker returns.
A systematic withdrawal plan is about income from capital, not accumulation. The real question is whether the portfolio can survive your withdrawals, the withdrawal increases you may need over time, and the return path you are assuming.
This estimate assumes the monthly withdrawal happens first and the remaining balance then grows for the month. That keeps the model slightly conservative for planning.
The most dangerous mistake is assuming that a portfolio can fund a lifestyle just because the first few years look fine on paper.
The more cash the portfolio must release, the less room it has to survive bad years, higher inflation, or weaker returns.
If your spending will rise over time, ignoring withdrawal growth can make the plan look much safer than it really is.
Use this next to the freedom calculator so you can compare the corpus you have with the cash flow you expect from it.