Antonyms for the phrase "most self-perpetuating" would include terms like "self-defeating," "short-lived," "unstable," "transient," "temporary," and "ephemeral." Each of these words suggests something that is not likely to endure or sustain itself over time. For example, a self-defeating system would be one that undermines itself or works against its own interests, while a temporary situation would be one that is only meant to last for a short period of time. By contrast, something that is "most self-perpetuating" suggests an enduring, stable, and self-sustaining system or process that will continue to thrive over time.