If a completely untrained person bought an entire shop worth of power tools and just started trying to build stuff, the potential for injury is astronomical. However, there's a right way to go about it. Every shop tool has a simple set of rules to follow. Learn the proper and safe way to use things, wear appropriate attire and safety equipment, pay attention, and the risk is very low.

Powertools are made to cut/grind/drill/etc... wood, metal, and even stone into useful shapes. All of these things are significantly harder than the human body. Of course the tools capable of doing it are dangerous.