I feel your pain, I have thousands and thousands of dollars invested in high quality tools (Klein, Greenlee, makita, amprobe), and I used to loan tools out to co-workers with similar results as you. Now I just don't loan them out. I need these tools to make a living. Now I keep all my tools under lock and key in the service truck, so no one can get to them. If it means being the bad guy then so be it.
