The time has finally come for geothermal energy

I've always been curious why a cost-effective widespread implementation of geothermal energy has never been considered a holy grail of energy production, at least not in the public debate. Much of the discussion is so focussed on nuclear fusion, which seems so much harder and less likely to be reliable.

Harder absolutely but "less likely to be reliable"?

If economically viable fusion was "cracked" what would the nature of it's unreliability even be?