There are some users who would actually rather pay $5/mo than use a free service. Thats because paying money gives the impression (real or not) that the service is more likely to stick around and be fixed when it goes down.
If I'm using cronjobs for some trivial unimportant task (like checking for firmware updates), I am not willing to pay. If I'm using cronjobs for super important competitive analysis, sure I'd pay.