multiplying $5,000 a day by so many years is a silly comparison

Sure.

it ignores the dominating factors to building wealth

It ignores the existence of wealth by focusing on income. And it neglects where income comes from.

Billionaires shouldn’t exist but also they don’t exist because they stuff X dollars under their mattress every day.

Something of a joke about the modern billionaire is how much debt they're carrying around. You don't become a billionaire by having a high salary. You become a billionaire by getting access to enormous volumes of low interest credit, in order to monopolize a limited stock of productive capital. It isn't like being an employee with a sky-high salary so much as it is a member of an elite club with access to amenities nobody else is allowed to use.