There is a concept called “bounded rationality,” which means people act in a fairly rational way when making decisions and account for all the information they have.
The problem is that the information they have is always a subset of all the existing information that could be useful in making that particular decision. In particular, people usually miss information about more distant parts of the system in which they’re operating.
This explains why intelligent people sometimes make stupid decisions.
In fact, really intelligent people are constantly at work to improve the quantity and the quality of their information and Eliminate bias systematically. When making a decision, they are not just considering the available information but also wondering what other information they might need right now.