I would gladly pay for 5 hours of training for a combustion endorsement, if I could avoid fuel costs for 40+ hours of training to get my private certificate.
Fuel isn't the dominant cost in flight training. (Source: I bought my first airplane during flight training and have been flying for almost 2 decades now. Fuel is more than a rounding error, but tends to run around 1/4 of my all-in costs.)