In about 10 years your buying power could be cut almost in half. Just look at what a car cost 10 years ago versus what one costs now. Some years ago, I decided to take parachute lessons. Fortunately, you don't have to be perfect in the stock market in order to be very successful. If you are willing to take lots of small losses and let your winners run, you can obtain a very high rate of return over a long period of time.
Losses are a very important part of a successful investment program.
And, since it is not possible to be perfect, you can make more money by limiting your losses rather than trying to never have any losses. One of the simplest ways to limit your losses is actually one of the most effective ways too. You will probably save much more money by being out of sharply declining stocks than you will forgo by missing a major upward move in a stock after you have sold it. And, you will still have most of your funds available for the next opportunity. By the same token, there is no rule that states that you have to sell a stock just because you have a profit.