Do you have any personal experience with Kratom? Of course, like myosin said, there has been cases where Kratom was laced with something else and caused sides that weren't directly the effect of the Kratom. Also, again as myosin stated, too much of anything isn't a good idea.
I work two jobs and still suffer from insomnia. Kratom is the only thing, other than prescription drugs like Ambien or Lunesta, that helps me sleep, so to me, it's been godsend.
I use it twice a day myself. Rotate your strains so you dont build up a tolerance. I didnt sleep for nearly 35 days coming off prescription opiods and then suboxone. That was pure torture. Im not too concerned about a little kratom withdrawals if i decide to stop.
I'm not denying your friends issues, but I honestly can't see how someone gets hooked on this stuff as a legit addiction.... I've been using it every day for months... do I feel different if I miss a day? Sure, but not addiction... not being a jerk, but maybe their stuff got laced with other things or they aren't fully upfront with you. A PSYCHOLOGICAL addiction, MAYBE as anything else that makes you feel good, ie weightlifting, but physical? Hard to fathom.