I might agree that it is potentially self sabotaging... but I wouldn't consider it SI. There are lots of reasons people stop taking meds, and I don't think they suit everyone. In the UK prescriptions are just £7.20 (or free if you're on benefits) but I know cost is a factor in other countries, depending on insurance coverage.

Stopping taking/refusing to take pills that may or may not help you, doesn't seem quite the same as picking up a blade or a lighter to your own flesh. Not to me, anyway.

(But, FYI: I do take my meds, as I believe they help me to function and prevent me from crying - for the most part at least... )