at today market price for FSD, $12000, it will take full 60 months of the monthly subscription to make it even. If someone
1) not using the FSD on monthly basis, or
2) trade in the car before the 60 months mark
it is better to pay the monthly subscription whenever they need. I would do monthly subscription when I need, and I do not even know if I would be qualify for the "beta" driving as well.