3. Ignore History at Your Own Peril (or, Everything Eventually Becomes a Trade):
You cannot be in the market very long and grow attached to anything, as everything will eventually disappoint you. I call this my universal entropy theorem of investing, and it's why everything -- from Microsoft to the 10-year bond, from Apple to gold -- eventually goes to hell. (Just look at the stocks tossed from the Dow Industrials for more evidence).
Gold has run up only be to trounced in repeated massive selloffs: 1915-20, 1941, 1947, 1951-66, 1974-76, 1981, 1983-85, 1987-2000 and 2008. And now add 2013 One would anticipate more selling for the next two years .