...receives message whilst scuba diving...spits out regulator in frustration...drowns. Never gets to send message from the future so doesn't drown.

Timeline broken, existence ends except for an endless five-year loop.

Woops!

The sequence of the numbers is not important and it's not all or nothing (5 correct numbers would still net a decent amount of money), so there's a chance that I'd recall enough to make use of it anyway. But it's a good point, this kind of thing hinges on the specifics of how the sentence is transmitted much more than something like "take out fire insurance" or "don't trust X".