The anecdotal evidence is that most child abusers started with CSAM and continued escalation from there; not that they would have been abusers except for CSAM.
While it has never been proven to be a casual link, Ted Bundy, Brian Mitchell, Mark Bridger, Jeffrey Dahmer, and now Bryan Kohberger all accessed violent pornography before taking their actions. Dahmer stated it was his ritual - consume violent pornography before finding the next victim. Bundy meanwhile stated it was the tipping point for him psychologically, more than any other known factor, even describing it as his "fuel."