Harking back to when fusion power, from a 'stellarator in your cellar', was reckoned but a decade or two away, as was AI, the snag was getting
some fusion neutrons turned out to be real-easy. Too easy, in fact, just 'Science Fair' tech, Getting any-where near the density-temperature 'product' where fusion becomes 'positive balance', never mind self-sustaining, turned out to be horrendously harder. I've seen analogies made between the BCE-ish Aeolipile and the steam turbine, with detour via Watt's clunky whatsits...
en.wikipedia.org
The laser/beam induced fusion approach also had a long history of false dawns. Remember BIS' Daedalus ? Its zapped-pellet pulsed-fusion propulsion ? Rather than Orions' mini-bomb thrower ??
IIRC, the Daedalus team took advice from eg Culham on bang-stuff, made what seemed reasonable extrapolations...
Tangential, I'm told there's still on-going research into 'Cold Fusion', usually by other names, and perhaps some-one will figure WTF was actually happening.
My feeling is 'commercial fusion power' will need a hybrid approach. Already part-way as Tokomaks tend to have lasers, ion-guns etc etc in addition to the mag-systems etc. Akin to a blow-lamp for starting 'Lancashire' boilers, a glow-plug or spark-plug for IC engine...
Snag is I still cannot see more than 'experimental' fusion power delivered to utility grids before mid-century. I hope I'm wrong.
Wild card could be one or more of the 'inertial confinement' approaches. Development of an
efficient mu-meson 'factory' would empower that route, and a 'Polywell-ish' design may yet scale unto 'Yay !'
YMMV...