> Most people have a mental model of budgeting which is roughly linear. If you spend half as much money, your money will last twice as long. As you approach zero spending, your runway goes up to infinity.

Well sure, but if you have investments, then it's not zero spending you need to approach, but your annual investment returns...Which is basically what the rest of the page discusses.

The author is basically asserting that most people who budget assume a 0% rate of return on their investment. But since that's a nonsensical assertion, they instead rearrange the logic a bit to make a functionally identical statement which sounds less obviously flawed.

The content in the article is good, but it could stand to have the "most people think...but they are wrong" section replaced with something more friendly and inviting. I'm personally not a fan of articles that start assert that a bunch of people are dumb.

The author is going for a MMM vibe, but I think what makes his articles so successful is he criticizes behaviors instead of calling people dumb (usually).