> From there, it's "just" scaling up.

I suspect this wasn't your intention, but I feel this heavily undersells how much work is involved in "scaling up" to simulating a human brain. I wouldn't even say that it is inevitable, because there are so many unsolved questions and unknown-unknowns.

There are decades of research and we are still an unknown and large number of years away from doing this. Fusion power is more tractable that this.

It's not even clear whether our current approach to computation will ever be able to do this. We might need completely novel types of computers, maybe organic-machine hybrids.

I'm not even touching on the very real and serious ethical questions of simulating human level consciousnesses.