There's one major mistake that every investor makes, and you need to learn about this because if you don't, you are going to destroy capital in your portfolio. If you go and you talk to any sort of professional, they'll tell you one of the safest things you can do is take your hard-earned money and put it into bonds. But that's actually one of the dumbest things you can do, and I've got the data to prove it.If we go and take a look at longduration bonds, we can look at TLT, that's down 40% over the last 5 y ...