People waste energy because it's cheap.  People waste as much of it as they can afford to waste.    Look at a typical oven.   To cook a pizza in it, you have to preheat the oven.   This involves heating up all the metal on the inside of the oven, all the air in the oven, etc.   The oven is probably 50-100 times the volume of the pizza.  Then it's constantly wasting that heat (the exterior surface will feel warm due to shoddy insulation).   Then after the pizza's cooked and you take it out, all that heat that went into heating up the oven itself is vented and wasted.   If the oven were smaller and the interior of it were tiled with a strong insulator, you could probably cook a pizza with less than half as much energy.

Look at the stove.   Boil some water.   While you're doing it, a large fraction of the heat from the burner is bypassing the water and going straight to the air.  The sides and top of the pot are losing heat too.   If the pot had a very conductive bottom, insulated sides, and an insulated lid, it would surely waste a lot less energy and boil your water faster.

Look at your refrigerator.   Until you open it, every joule of energy that it's using is a result of inadequate insulation.   They idle in the hundreds of watts.

 Look at your windows.  When it's -10 outside, they're constantly hemmorrhaging energy in the form of heat that was produced with your electricity.   The interior of the window may have frozen condensation on it, while most of your room is kept at room temperature by a steady stream of wasted electricity.   In that case you're losing hundreds of watts of energy per square meter of window.   Windows are an extremely wasteful luxury if you intend to have any climate controls indoors.  Even double-pane windows are crap compared to some fiberglass insulation.  The smaller the windows, the better.

Look at the insulation in your walls.  It's not very thick.   If you didn't have huge windows bypassing everything, then your heating bill would be inversely proportional to the thickness of your insulation.   If your house was insulated properly, heating cost would be nearly zero (body heat and incidental electicity use, properly contained by insulation, would suffice to maintain room temperature inside, in any cold climate).  If you had even more insulation than that, you could use excess indoor heat as a power source for a generator that uses indoors as the hot reservoir and outdoors as the cold reservoir.  A couple feet of foam would suffice.