Right, but you "get it back" on the condenser surface, not in the fluid that needs to be boiled. At it is exactly the temperature gradient that you need to maintain, so cooling the condenser surface with the to-be-boiled fluid will work only to a point. There are systems that cool the condenser with the water before sending the water to the heater, but the rate at which heat flows is much slower than the rate at which the water must flow.

That's the problem with heat. It is not a source of energy. It is a store of energy, often one that simply needs to be disposed of.