"The way I see software, it gets better with use. It is not self-healing, but given that somebody is fixing the bugs that are found (which is often the case), then software keeps getting better with use."
It's got to be more nuanced than that. For example, software won't benefit from bugs being fixed if the rate of churn is very high, if new features are added rapidly and the size of the state space explodes. Times like that create technical debt. Surely technical debt isn't antifragile. Since we still don't know how to avoid it, it seems a stretch to say all software is antifragile.