6. Trusting without proof. The single biggest mistake of my financial life was naïvely trusting a group of people because I liked them and it felt right. I neglected to get proof that they were actually as they presented. Instead I went with my feelings and was deceived. By the time I figured out something was wrong, I was out millions.
Disregard your feelings when it comes to people and always look for solid evidence. If you are so close to people that you are not willing to ask them to provide evidence, make it a policy not to do business with them.