Technology

Most importantly, the projections of fusion being 30 years away depended on assumptions about funding, when political considerations made it so that we basically never came anywhere close to those assumptions:

https://commons.wikimedia.org/wiki/File:U.S._historical_fusion_budget_vs._1976_ERDA_plan.png

Fusion was never vaporware. We had developed working weapons relying on nuclear fusion in the 1950's. Obviously using a full blown fission reaction to "ignite" the fusion reaction was never going to be practical, but the core physical principles were always known, with the need for the engineering and materials science to catch up with alternative methods of igniting and harvesting the energy from those fusion reactions.

But we never really devoted the resources to figuring it out. Only more recently has there been significant renewed interest in funding the research to make it possible, and as you note, many different projects are hitting different milestones on the frontier of that research.

I wrote a school report about iter back in middle school or high school when it was still in the design process and still occasionally check their job listings because I would love to work there and on fusion but we still don’t know if it will ever work like we hit the scientific breakeven with inertial confinement but the scaling on that is terrible and I don’t believe we hit even the scientific breakeven with magnetic confinement

Then we still need to harness the energy from that turn it into work, turn that into electricity and distribute it with enough excess to pay for the whole system which is still a lot of hurdles we need to climb