Different happy chemicals produce different ways to experience happiness.
Endorphin happiness is triggered by physical pain. The body's natural morphine masks pain, which allowed our ancestors to run from predators when injured. Humans experience endorphin as euphoria, but it obviously did not evolve to trigger a constant feeling of joy. You would touch hot stoves and run on a broken leg if your brain were always releasing endorphins. Nature saves them for moments when they help you do what's necessary to survive.
Dopamine happiness is triggered when you get a new reward. When you see a finish line, your brain releases dopamine. It's nature's reserve tank of energy. Dopamine keeps you going until you catch the prey you've been stalking, even when the chase is long and frustrating. If you surged with dopamine all the time, your energy would be depleted when you really needed it. We evolved to save dopamine for those moments when an important goal is within reach.
Oxytocin happiness is triggered when we trust those around us. It promotes bonding between mother and child, and between sex partners. It's stimulated when you're with a group of like-minded people, or when you get a massage. But we did not evolve to feel oxytocin happiness all the time because there's no survival value in trusting people who are not trustworthy.
Serotonin happiness is triggered when you feel important. Animals release serotonin when they dominate a resource. Their serotonin falls when they cede a resource to avoid conflict. Being one-up feels good, but conflict can cause painful injuries. The brain is constantly analyzing information to balance the risk of pain against the satisfaction of winning.
This is all very well, Furry Happy Monsters, but for me it has always been booze that smears the vaseline on the lens of reality.