[grecy]

The reason that earning more never works out is because the more you work (and attempt to earn) your actual money in hand asymptotes and you're not getting reward for your effort & time.

Taxes go up the more you earn. You'll spend more on food and stuff the more you work because you're more tired, you'll spend more when you earn more (b/c the goldfish fills the bowl), you will be surrounded by people who earn more, so you'll live the "high life", etc. etc.

Also it's a bit of a play on words, because when you spend less, you'll realize you need less, and so it will appear you have more.

[Franciscouzo]

Of course you're not going to achieve FIRE if you spend all the money you earn, the whole point is to save the most you can, if you can earn more of course, go for it, but for a lot of people it's out of reach, so it would be pointless to recommend that.