Your figures are incorrect and, as i stated, it's all a matter of investing in the right equipment and batteries.

If you buy a charger that can charge your batteries at 2C (use balancer) and 2 battery packs, you can do 2 flights (say 30 minutes together) and then take a 15 minute break, do 2 flights, and so on. If you want to fly even more, you buy 3 packs and 2 chargers.. then you can fly continiously.

If you fly so much that every minute count, electric would even be a better choice. When properly charged with a balancer, a current Lipo will last for 2 years.

It's all a matter of money. If you don't fly much or don't want a high initial investment, gas is the better choice (imho). If you're going to fly a lot and don't mind a high initial investment, if it means you'll save money in the long run, electric is the better choice.

In the end you'll probably end up doing both.