I practiced thai boxing for many years and it may sound odd, but I don't really see boxing as a violent sport, no more than let say soccer. I've never hit anyone (other than on a ring) and never will, and I hate violence as much as most people. In the context of boxing I see hitting as a technical move.
Besides the occasional bruises, rare broken ribs or black eyes, I've never injured myself. Most of the time, you practice with control and with various protections, wary of your partner level.
Competitions are more violent, but even there, there's a gradation. Fighters are matched by skills and weight, depending on their level use protections (helmet, shin guards), and the referee is there to stop the match if needed.