No doubt about it that markets can remain irrational longer that you can remain solvent. Especially when dealing with speculative investments! That's why I always caution people to never invest more than they can lose. If you're doing that, then it's the long haul that matters, not the day-to-day fluctuations. On the other hand, it's a different matter for short term traders, but, nevertheless, they too should be focused on best practice risk management, trading in appropriate size, using good stop loss strategies and the like. In short, no matter how correct we are about the long term, irrational short term fluctuations can break the bank if you're not correctly positioned.