This is the main enemy of online courses, its not the competition, its the the lack of compromise from the user in part because everything is "virtual" and you don't feel any major regret for dropping out.
Coursera and all the others should focus on this part of the problem, not by asking for more money, that will just make them less likely to try again. Maybe calling the student after a few weeks of inactivity could be one way to help, another one may be to create and maintain local study groups (having free food is always a good incentive), another one is to be "paired" with another online student so you feel a little social pressure.
>another one is to be "paired" with another online student so you feel a little social pressure.
This is the biggest difference for me between courses that I have started and courses that I have finished. Meeting with someone in real life, even if it's just for an hour a week, easily creates the pressure to continue on that an email reminder simply doesn't do.
Coursera and all the others should focus on this part of the problem, not by asking for more money, that will just make them less likely to try again. Maybe calling the student after a few weeks of inactivity could be one way to help, another one may be to create and maintain local study groups (having free food is always a good incentive), another one is to be "paired" with another online student so you feel a little social pressure.