Because fusion will let us do things that we may not be able to do right now. Especially if fusion takes the form of one of the non-ITER-style reactors that mer

Because fusion will let us do things that we may not be able to do right now. Especially if fusion takes the form of one of the non-ITER-style reactors that merely costs millions instead of billions, it may still be by far a more environmentally-friendly power generation method; no massive construction of square miles of solar panels, no need for windmills, power for space craft and space stations. Things like desalinization may be far more practical with fusion. In the long term, we won't just need power as good as today; we need something much better than today. The next step after fusion would be some form of total conversion, of which the only feasible chances seem to involve black holes, so, a ways off yet. Probably not save to use on a planet.