I believe some people "go crazy" from meditation because they simply don't follow the instructions. They start to feel or experience something, get excited about it, and start trying to recreate it or strengthen it. At the same time they build up delusory ideation around the experience.
Most important things in meditation training: lengthen attention span, reduce the yappy ego, reduce attachment.
Least important things: experiencing energy flows, sensations of being charged with power, all that.