However there are indicators and fudemental facts that some of us utilize to make a rational guess as to what the price will be in, let's say, the time span of a week. These indicators being news, announcements etc. On the other hand you also have fundemental facts. If the price crashes 'hard' you know that at some point (most of the times an old resistance or support level) traders will start buying the dip. For example, the china dip. At around $3200 people really started stocking up on there bitcoins before hitting a low in the high 2900s. Now we're trading at 4300$ again. If you bought in at $3100 you nearly made 40% on your investment in a week or two.