Why do so many wise teachers abuse their power?
A wise teacher would never abuse his or her power. It’s as simple as that. Those teachers you mention were not actually wise at all. They were no doubt intellectually brilliant and very eloquent, but as one ancient book of wisdom says, “Wisdom is proved right by her actions” (Jesus speaking in Matthew 11:19.) The abuse of spiritual power is a hallmark of those who think more highly of themselves than they ought. That is not the same as those who struggle to live up to (perhaps) impossibly high ideals, then become so depressed at failing that they want to take their own lives. I speak only of those who use their position / authority to violate other people in any way (physically, emotionally or spiritually). All abusers will answer to God for that. I believe Jesus set the perfect example and He never fell into the trap of abuse because He was perfect. None of us are. That is why we need Jesus. I would encourage you to consider Him.