There is a lot of bad advice about almost everything people are interested in: learning, nutrition, exercise, personal finances, career development, how to code, how to write, relationships, running a business...

Some of it is survivorship bias - often influenced by privilege/luck - being confused as skill or insight. Some of it is people who aren't very reflective, scientific or logical in their thinking making poor guesses or estimates with a lot of unmerited confidence. Some of it is more cynical: if somebody is buying, they're selling.

As a civilisation we still aren't great at root cause analysis of success, it seems.