1) It's not the holy grail. It's been shown that if our energy consumption continues to grow along its current trajectory, then the temperature at the surface of the earth will reach the boiling point in several hundred years. Now, presumably the growth of our energy consumption will slow down at some point. But what this thought experiment demonstrates is that any power source that generates denovo heat on the earth is part of the problem. Ultimately, the source of our power will have to be the sun.
2) Even if a fusion generator could be created, it would also have to be cheaper than current sources of energy such as solar. Good luck. This hurdle may be more difficult than creating the fusion generator in the first place.
3) However, the real answer to the question: There have been so many failed predictions about when we would have practical fusion power, that no one believes in it enough anymore to put even more money into it.