How is electricity wasted?
You are confusing electrical current with electrical energy.  Given how you express confusion over the fact that current can go in a loop yet energy is wasted, I think that you are also tied to the notion that energy must be tied to the matter that happens to be carrying it.

Yes, current goes in a loop.  We do not, on an everyday basis, create or destroy electrons*, and electrons strongly repel each other and are strongly attracted to atomic nuclei, so any current that flows is forced to loop around and come back to the source.  This does not mean that energy does not flow, however.  If I connect a battery to a pair of wires here, then the battery adds energy to any electrons flowing through it from its positive electrode to its negative electrode.  This potential energy per electron is seen as the voltage of the battery.  If those wires are connected to a light there, then current will flow through the light.  The energy imparted in those electrons in the battery will be converted to light and heat in the light.  If you ignore any losses in the wires, then the energy has flowed from the battery to the light, but the net number of electrons has stayed pretty much the same everywhere.

If you're still caught up in the "how can electrons go in a loop but the energy goes from point A to point B" problem, then consider hydropower.  The sun shines on the sea.  It imparts energy to the seawater, some of which evaporates.  Some of that blows over mountains, and some of that rains down.  Some of that forms into a river, which someone has dammed.  The water impounded behind the dam is run through turbines generating mechanical energy.  Then the water runs back into the sea.  The water has gone in a loop.  The energy has been transported (with great inefficiency) from the surface of the ocean to the turbines in the dam.

Dunno if this helps -- it's always hard to know what will clear up a confusion.

* Please, please do not bring beta decay into this discussion.  Yes, electrons are created.  No, it is not on topic.