As someone with a 96+% 'failure' rate on Udemy/Coursera I honestly don't see the relevance of this statistic. Most people going to University are there primarily because they want/need the degree. That piece of paper is really valuable, perhaps even more so than the knowledge gained. The piece of 'paper' offered by Coursera/Udemy etc. has basically zero value, so the people taking those courses are doing it almost exclusively for the knowledge they offer. Once you've learned what you wanted to learn from the course there is very little incentive to go the extra mile and go for the 'completion'.