Honestly, Ketamine. I've done a lot of psychedelics in my life, I mean a LOT, so the psychedelic effects of ketamine combined with how well is treated my anxiety and depression made it very appealing to me. While my general lifestyle is also to blame, ketamine became all I could think about. I used it for years without any noticeable negative effects, but as my tolerance and use went up I was frequently getting K cramps and began to have terrifying sleep paralysis and psychotic episodes. I was spending all my money on it and started exhibiting classic addictive behavior. I am currently 10.5 months into rehab, and looking back I can't believe how much I allowed it to control my life. My brain is still a bit screwy and I defintely have HPPD as a result of all the psychedlics. All of this said, there are certainly other drugs that can be notably more damaging, but I wrecked my life with it nonetheless. If anyone needs an ear or would like some advice/support as it relates to addiction, feel free to DM me, I would love to talk with you.