Then I finally reply that my experience so far - even in this realm of merely human possibility - does seem to indicate that, once you sort yourself out a bit and you aren't doing quite so many other things wrong, striving for more rationality actually will make you better off. The long road leads out of the valley and higher than before, even in the human lands.
—Incremental Progress and the Valley

It has been observed that when someone is just starting to learn rationality, they sometimes appear to be worse off than they were before. Someone else may then allege that after this person learns even more about rationality, they will finally be better off than they were before they started. The period before this improvement is known as "the valley of bad rationality".

Non-post example:

This comment by Scott Alexander on Bayesians vs. Barbarians

See also

Valley of Bad Rationality