<prompt> Human: Last week the market went down a ton, I invested, and now it went up. Seems pretty easy. The trick is to invest in things you know wont go to zero, like single companies. Such as VTI, which is an ETF for the total stock market. Theres no way that will go to zero. If it does, weve got bigger problems, like Russia just primed a nuke and started WWIII. Seems like a pretty easy rule to follow: if the entirety of the market sinks 5-15, invest and itll eventually go back up.  <response>: There are two problems with this approach.You are holding money in cash while waiting for The Dip. This means you lose out on potential gains the longer the market goes without dipping.You dont know where the bottom is. You may have guessed correctly this time, but the market dipping 5-15 doesnt mean it wont dip another 5-15. 