The problem is that inflation destroys the value of money quicker than you realize. Nice houses can cost $30M in alpha cities. $20M is a goal post that will need to be moved regularly. It’s too difficult to say what is “enough”.
Inflation destroys the value of money, not the underlying goods or services. Whether there are 100 dollars to go around or 10 billion, for the same "physical context"/material reality a rule along the lines of "no more than %5 of total wealth accumulated in 1 person's account" seems inflation-resistant.
If this seems insane to you, consider the insanity of trying to define a fixed container size with an infinite flow of water.