It's not arrogant at all, it's a rational, evidence-based prediction. I recommend https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-drawbacks-of-fusio

It's not arrogant at all, it's a rational, evidence-based prediction. I recommend https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-drawbacks-of-fusion-energy/ https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-d... for an initial introduction to why the idea of fusion by the end of the century is only a "maybe". As a sort of representative summary of the situation, the ITER project has been in progress since 1988 - 34 years - and hasn't yet achieved fusion for more than about 5 seconds. On top of that, by design, it will never be net energy positive - the tens of billions of dollars and decades spent on it are purely to produce a proof of concept for sustaining a fusion reaction. Turning that into something that can actually act as a source of energy is currently still at the "unsolved problem" stage. We can't even write a project plan for how a viable reactor could be developed, because we simply don't know. As such, there's no realistic scenario in which this situation somehow turns into viable fusion power before the end of the century, short of an unexpected major breakthrough. While such a breakthrough is conceivable, it's not something you can base a strategy on. The responsible position is to recognize that we can't rely on anything useful happening in fusion in this century. One other point about the "think back to 1942" comment is that extrapolation only works when you have relevant data points to extrapolate. The technological advances since 1942 have been nothing like the advances needed to exploit fusion. Fusion involves literally recreating the conditions in the heart of a star, but without the enormous mass of a star to provide the necessary pressure. There's no precedent for this in our technological history. Nuclear fission was trivial by comparison - nature does all the real work, all you have to do is arrange the fissile material appropriately. That's not the case for fusion. It's an incredible achievement that we can produce a fusion reaction for 5 seconds, but there's no guarantee that we're going to be able to turn this into something that can be sustained day in, day out, and that generates more energy than it consumes.