The word "more serendipitous" implies that something is happening by chance or luck. Its antonyms, on the other hand, suggest that events are predictable, planned, or intentionally controlled. For instance, the phrase "less serendipitous" implies that something is happening with less chance or luck involved, while "premeditated" connotes a deliberate, thought-out event. Other antonyms could be "intentional," "calculated," "deliberate," "systematic," "disciplined," or "methodical." These words convey the idea of purposeful actions or decisions, rather than mere coincidences or unplanned encounters. Ultimately, the antonyms of "more serendipitous" highlight the absence of chance, spontaneity, and fortuitousness.