The calculation below assumes that invesment value does not change.

Unfortunately, because of the above assumption, your calculations are meaningless. Without accounting for real-world swings in investment valuations, its extremely easy to say 'as long as I pull out less money than I make, accounting for inflation, I can't lose'. You don't need a spreadsheet to tell you that.

Try going to Vegas to with those assumptions. Here is a great Vegas betting strategy. Start with a unit bet. Each time you lose, double the bet. Each time you win, put down a unit bet. In theory, you can't lose, but in the real-world, it's impossible to implement.

Zev