I'll Translate the graph,
To get a return in 5 years on your time/money spent :
If the routine is used once a day and you can save 5 minutes each usage,
you can spend 6 days working on it.
If the routine is used once a week and you can save 1 minutes each usage,
you can spend 4 hours working on it.
If the routine is used once a month and you can save 5 minutes each usage,
you can spend 5 hours working on it.
some of the results are rounded with poetic licence.
If there are 10 paying users, all the better
As I said, perspective.
added:
Of course, the lessons learnt from programming are invaluable, so usually it's worth the time