Disciplined investing is rewarded by the financial markets because capitalism, by and large, works. For investors to put their capital at risk, there needs to be a commensurate expected return. This is finance. Everything else is just details.

Investors are rewarded for taking risks. That means that sometimes that return doesn’t appear. In fact, if you look at the equity premium, or the returns stocks minus the returns of short term US Treasury bills, it’s actually pretty rare for the premium to be close to the average.
— Read on retirementresearcher.com/the-art-of-disciplined-investing/