Investing is the only profession in the world where experience can be just as much of a drawback as a benefit. Every market cycle is different and just because you were able to successfully navigate through one downturn, does not mean you will be able to get through the next. 

The list of formerly great investors who’ve blown up due to overconfidence in their abilities is endless. The latest figure is Carl Icahn, formerly a fierce corporate raider he’s lost somewhere in the region of $9bn shorting equity markets over the past decade and is currently engaged in a fight with the short-seller Hindenburg Research (which has cost him another $10bn plus).