No. 1: Not planning for the future
If people are asked about their future, they can usually paint a fairly happy picture.
They will be retired, their bills will be paid off, and they will roam the world while living off their perfectly adequate nest egg.
The reality is that many individuals have no plan for the future. They may have desires, but their current habits will never get them to their desired state of living in the future.
Does a financial plan guarantee success? Of course not. However, the mistake that many people make is not having any sort of long-term financial strategy and hoping that things will simply work out somehow.
Thinking that way may reflect the positive outlook of the individual, but it may also mean that they will someday experience disappointment at their lack of serious financial planning.