Let's talk about this "principle"
DO you think this is an always-right rule?
How do you trade ?
This is the basic principle behind cryptocurrency and even outside of it. What goes up will also go down and what goes down will also go up. That is something that we can readily observe. In crypto, for example, when the prices are very low, there is an expectation that they will go higher in the next days. It is because there will be massive buying. And if the prices are also very high, there is an expectation that they will also go down in the days to come. It is because there will be selling or dumping for sure.