Humans will not achieve commercially-available sustained fusion reactors until they have mastered gravity control. It takes a sustained gravity field to compress the nuclei sufficiently for fusion to take place. Heat and inertia are good starts, and may be sufficient to heat a kettle for tea, but if you want to light a city, you need a gravity well to keep it going.
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The mere fact that science may not yet adequately explain an object, event, or experience does not mean the immediate explanation should automatically default to a conspiratorial, extraterrestrial, paranormal, or supernatural cause.