•Why it earns a slot
Why it earns a slot: this is the source text for half of America's self-help vocabulary, decades before self-help existed as a genre, and the actual argument is sharper and stranger than the inspirational-poster version most people know.
Thoreau moves into a self-built cabin to prove that most of what people spend their lives earning was never necessary in the first place.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.