Completion is the one metric course platforms report least and creators discuss least. Where it has been measured properly, the picture is consistent: across thousands of open online courses, median completion sits near 12.6%, and most cohorts fall below 10% (Jordan, 2015). Paid courses do better, but not by the margin most people assume.
Price does not fix it. Neither does production quality. A course recorded on a phone and a course with a film crew abandon at similar rates, because the reason people stop has almost nothing to do with the teaching.
It has to do with design. Nothing told them where the end was, how close they had come, or why today mattered more than tomorrow.