Through the whole time the market has gone up I've always heard...

Through the whole time the market has gone up I've always heard from someone about the coming crash. Eventually it does come and someone takes credit for getting it right even though they were predicting it for the last 20 years while the markets have gone up. The quote a broken clock is correct twice a day comes to mind.

If you are worried about a crash to the extent that it affects your sleep at night or ability to buy stocks then make sure you do get out because the market is no place for you to be. This is for health and psychological reasons rather than for possible damage to wealth.

If you are trading stocks and the possibility is at the back of your mind simply do what rational traders who make money do and make sure you have a stop loss on your stocks at a level you are comfortable with.

Personally I see a market crash as a buying opportunity to accumulate lifetime assets and wealth.