In the truest sense, a person is an addict to anything when he is physiologically or psychologically dependent. Since we cannot be physiologically dependent on a SAK, it boils down to psychological dependence.
I am definitely psychologically dependent on SAKs, both in terms of their acquisition and hoarding, but also as to daily carry and usage. When I watch Netflix with Mrs. Powernoodle, I am usually playing with a Swiss Army Knife at the same time. So yeah, I'm definitely an addict.
But we are not addicts in the same sense that one is addicted to alcohol or drugs, as those addictions are defined in part as a behavior that one continues despite adverse consequences, as well as showing physiological dependence. We generally do not experience adverse consequences from buying or carrying SAKs, so long as our mortgage bills are still being paid.