All my statements are based on the assumption that electrons
have 0 electric potential after they go through the last
load or is at the end of the circuit.
That's not what "potential" means. Individual electrons cannot "have potential," since potentials are always measured between two points. Depending on your choice of the other point, a single electron can have many different potentials, all at the same time. (It can have an infinite number of potentials. It can even have negative potential, so would that mean it's carrying negative energy? No, that's not how potentials work.)
Huh, is it big-wall-of-text time again? Guess so!
This problem becomes far easier to understand if we pretend that electric potentials are like altitudes.
When the babbling brook has passed over the wooden waterwheel, and the water falls downwards, and some work on the wheel has been performed, and the millstones have ground some wheat into flour ...are the exiting water-molecules now at zero altitude? No, since a molecule of water cannot "have altitude," and besides, "zero altitude" does not exist. Altitude is always measured between two points, and we get to choose the second point. If our altitude-reference is up at the water-level above the waterwheel, then the downstream exit is at negative altitude. Does this mean that the water molecules must have sucked energy out of the waterwheel? Has some negative work been performed, as the millstones ground the flour? No, that's just silly, and it rubs our nose in the cause of the misunderstanding.
To understand the waterwheel, we need to stop thinking about absolute altitudes or about "energy stored inside a water molecule." Instead, the stored potential-energy is out in the system as a whole. (Actually it's stored in the gravity fields of the whole landscape, and not stored inside the water molecules of our babbling brook.) When we lift a liter of water higher above ground, we aren't injecting some sort of strange energy into the inside of each H2O molecule. Instead, we're stretching the gravity fields. The water molecules remain exactly the same, whether they're up in orbit, or sitting on Mt. Everest, or down in the Mariana Trench. Looking at individual molecules tells us nothing about gravitational potential energy. The energy is stored in the empty space, in the attractive fields between the molecule and the planet. In a certain way, the "height" itself is the energy. (Well, height-and-a-lifted-mass.) The potential energy is found in the empty space where the altitude exists. But also, if we lift two molecules rather than one, we double the stored potential energy, while the altitude stays the same. Potential energy is a strange combination of mass as well as altitude. The energy is stored in the system as a whole, not inside the mass-particles being lifted.
And, similar is true of electrons.
Electrons don't "have potential," and they cannot store energy inside themselves. The energy is stored in the surrounding field-patterns. Electrical energy travels just outside the wires. Not inside the copper. For electronics, "altitude" becomes "altitude in an e-field," rather than the lift-height in a gravity field. With circuits, their stored energy ends up in the EM fields outside the wires. When coils store energy, it's stored in their magnetic fields, and when capacitors store energy, it's stored in their e-fields. With circuits, both of these are happening at the same time.
Closed water-loops are weird in another way.
If our wooden waterwheel is powered by a distant water-pump, where the pump lifts the exit-water back up into the upper brook, then what happens if we choose the upper brook as our height reference? In that case all the energy is being delivered by the lower exit-stream! It's flowing backwards, and at negative height. Multiply the flow rate by the height to obtain the watts of energy-flow. Negative times negative gives a positive, so we find that energy is going from pump to waterwheel, and entirely flowing through the lower brook.
Yet if instead we choose the lower brook as our height-reference, then all the energy is flowing in the upper brook, and none in the lower! (Heh. Or, if we choose our height-reference at the midpoint, at the axle of the waterwheel, then our calculations will "prove" that each brook delivers half the energy-flow.)
Where then is the true location of the flowing hydraulic energy?
This is much the same problem with circuit-energy. The electrical energy isn't inside the movable charges in the conductors. And, the energy isn't all flowing inside one wire, with zero energy in the second wire (because energy cannot flow inside metals in the first place; instead it all flows in the EM fields outside the wire surfaces.)
Here's one way to cut through the confusion.
Start with two long wires. They're full of protons and electrons, equal amounts, to give neutral net-charge. Now move some charges from one wire to the other. This means that one wire is now negative, the other positive, and energy has been stored in the e-fields extending between them. The two wires have become the two plates of a loooonnng capacitor. When we move some charges, the e-fields spread along the wires at light-speed, and occupy the entire space surrounding the two parallel wires. Notice that if our charge-pumping was performed at one end of the wire-pair, energy is now available at the other end! A long capacitor is a method for transmitting e-field energy.
Next, connect a resistor at the far end of the wire-pair. This "discharges" the capacitor and heats the resistor. The e-field energy found in the space between the wires will all rush into the resistor (it propagates at the speed of light.)
Which wire delivered the flow of energy? Both, obviously. Or neither, since the energy remained entirely outside the metal. There were no "energized" electrons or protons here ...any more than lifting a rock off the ground can create "energized" silica molecules. Instead, we injected energy into the whole "capacitor." Then, the resistor took energy out of the whole "capacitor." The energy traveled as EM waves at lightspeed.
Forest versus trees. If we "zoom in" and look at just one wire, that means we've started ignoring the system-as-a-whole, and we've gone up a conceptual dead-end.
The energy was stored in the entire 2-wire capacitor, and not in one of the wires, and certainly not inside individual electrons.
BELOW: a battery, a resistor, and the EM energy-flow in the electric circuit. Red is the magnetic field, grey is the e-field. The circuit as a whole delivers energy from battery to resistor. (The "entire forest" does it. Individual "trees" do not!)