This is a crazy idea that I'm not at all convinced about, but I'll go ahead and post it anyway. Criticism welcome!

Rationality and common sense might be bad for your chances of achieving something great, because you need to irrationally believe that it's possible at all. That might sound obvious, but such idealism can make the difference between failure and success even in science, and even at the highest levels.

For example, Descartes and Leibniz saw the world as something created by a benevolent God and full of harmony that can be discovered by reason. That's a very irrational belief, but they ended up making huge advances in science by trying to find that harmony. In contrast, their opponents Hume, Hobbes, Locke etc. held a much more LW-ish position called "empiricism". They all failed to achieve much outside of philosophy, arguably because they didn't have a strong irrational belief that harmony could be found.

If you want to achieve something great, don't be a skeptic about it. Be utterly idealistic.