Nuclear fusion is possible but is it practical to produce energy?

Nuclear fusion appears to be a near-limitless source of clean energy, but so far, no experiment has generated more energy than has been put in.
Nobody can make energy out of nothing, as the law of conservation of energy has made it quite clear that energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another.
Stars can perform nuclear fusion because of their immense gravity. Laboratories can do it due to their tremendous consumption of electricity. If fusion energy is transferred from the gravity of stars or from the high-powered lasers at laboratories, it’s impossible for fusion machines to generate more energy than they use.
In contrast to fusion machines, fission devices can produce more energy than they consume because heavy elements do have extra energy. In thermonuclear astrophysics, elements heavier than iron are being formed by absorbing nuclear energy inside a very large exploding star called supernova. In other words, fission energy comes from the explosion of ancient stars.
When it comes to fusion, I have found neither theories explaining where fusion energy comes from, nor cases indicating that light elements have extra energy. The success of hydrogen bombs doesn’t mean that fusion reactors have a future, because most energy of the bombs actually comes from fission.