Alexander- Thanks for the BB post. We decided to use a 5 year ROI (it's described at the bottom of the post) because there are actually 3 guides (beginner, intermediate and expert) and in some of the tasks, there is no investment and no finite lifetime (e.g. driving slower) So to try to normalize the ROI and make it feel like an actual motivator to people, we tried to show that these things can actually achieve real return on investment, or even "profitability" in only 5 years.

As for showing -50% ROI rather than 50% (meaning half of your up front investment is recouped) - I think we could have gone either way on that.

Regardless, thanks so much for engaging with the comments - check out the other two guides - you should see them in the side bar of the experts guide. Looking forward to seeing you around the site!