That's not entirely true. It ignores the effects of taxes on the withdrawals and/or returns unless you are including them in the 4% you are living on. For example if you are pulling money out of a 401K, you'll be paying taxes on that money so you can't live on all of it. You either need to withdraw more than 4% or you need to live on less.
Inflation is the great destroyer of wealth when it comes to retirement planning. For example, if you currently live on 100K after taxes per year and wanted to do the same retiring 30 years from now, with 4% inflation you'd need roughly $325K per year to live on after taxes. That's a sizeable jump for people that aren't thinking of it when planning how much they will need to retire.
I really can't tell if you're being intentionally obtuse or if you are literally just incapable of basic math. You certainly put strong evidence forth for the idea that medicine is the path for all of the people who are good at science but terrible at anything having to do with mathematics.
Very simply, your retirement income goal should be your
PRE-TAX drawdown goal. So if you want to draw down 100k pretax, you have to have $2.5 million saved. Now, as to inflation- it is not the destroyer of wealth when it comes to retirement planning, for reasons I already explained. You invest to make 8% a year, on average. You draw down 4% of that, leaving 4% to be added to your nest egg. That 4% covers your inflation, and then some. Let's look at how this works over a four year period:
Year 1, $2,500,000
Nest Egg after 8% Gains: $2,700,000
Draw down (4%): $108,000
Nest Egg after Drawdown: $2,592,000
Value of 100k after 1 year of 3% inflation: $103,000
Year 2, $2,592,000
Nest Egg after 8% Gains: $2,799,360
Draw down (4%): $111,974.40
Nest Egg after Drawdown: $2,687,385.60
Value of 100k after 2 years of 3% inflation: $106,090
Year 3, $2,687,385.60
Nest Egg after 8% Gains: $2,902,385.60
Draw down (4%): $116,095.06
Nest Egg after Drawdown: $2,786,290.54
Value of 100k after 2 years of 3% inflation: $109,272.70
Year 4, $2,786,290.54
Nest Egg after 8% Gains: $3,009,193.78
Draw down (4%): $120,367.75
Nest Egg after Drawdown: $2,888,826.03
Value of 100k after 2 years of 3% inflation: $112,550.88
Your nest egg grows faster than inflation, even with the 4% drawdown. That's why it is used, and why it was determined to be the ideal drawdown rate by a mathematician/financial planner/MIT educated rocket scientist. We get it, you want to live a lavish lifestyle and never retire and that's fine. But don't say retiring is impossible- it's very easy to do, and the math is extremely simple. You just don't want to live the lifestyle that comes along with early retirement. I'm fine with 50k a year pre-tax, 100k is actually pretty extravagant for my tastes, hence my personal 2.5-3 million goal.