There are many questions when it comes to investing, but in this book Ken Fisher narrows it down to three most basic questions every investor should ask and also touches upon behavioral psychology. Our brains, our very human brains that make us prone to making very human errors, sometimes work against us when it comes to investing. Basically, our brains are wired for survival. And one means of survival is avoiding pain--so how does one avoid pain and survive when it comes to stocks? By getting out when the getting's good--which is often the worst time.
As Ken Fisher writes in The Only Three Questions that Count, "What the heck is my brain doing to mislead and misguide me now? To blindside me? Another way to ask this is, 'How can I out-think my brain which normally doesn't let me think too well about markets?' This is the realm of behavioral psychology. One thing you can come to know no else can is how your individual brain works--what it does well in relation to markets and what it does badly and how to re-program yourself to not use your brain in the ways it works worst for markets. Few investors have spent any material time trying to understand how their own brains work... You can learn how your investor’s brain works to hurt you and when you do you will know something almost unique since your brain is partly like other people's and partly yours uniquely."