In cryptocurrency we rely on prediction and in the process of the observation, there are some prediction become false while some are accurate. We can't neglect prediction in the cryptocurrency market.
I somehow agree to what you have said, this is a speculative market so predictions do have its part.
But I'd say that we don't fully rely on them as the market has its own factor and basis on how it shall move. While those predictions are no doubt moving the market and affects it.
These factors we can use aside from speculation is what we call market analysis.
In market analysis we look at previous data, compare trends and patterns. Markets can be predictable in a way where you can have a pretty much vague idea of which direction the market might point to but it is quite literally impossible to predict a specific price at a specific time period.
These speculation comes from analyzing the market and the overall crypto scene. Once a person starts predicting a price, everyone else will soon follow.