> Fusion is in theory something that could give us true energy abundance.
The biggest problem is the 'in theory' part. With current plausible designs, the vast majority of the fusion reaction's energy is carried away by high-powered neutrons, which are entirely waste products.
Some do, but most of them escape from the plasma, carrying away energy, and need to be captured by the neutron blanket. This amounts to a whopping 80% of the reaction energy.
The real dream are fusion reactions which don't produce neutrons, such as H1+H1 or much more realistically, H2+B11 (though still many times harder than H2+H3).
