It was a controversial program from the start, and some people are still a bit salty about the whole thing.
The obvious issue was of course the money (and how none of it went to me).
But the deeper issue that few people articulated was this: It did not follow the normal scientific process. Normally scientists start with a hypothesis, design an experiment to test it, and finally they solicit funding to run it.
The human brain project didn’t start with a hypothesis. Instead it was a general fact finding mission, to systematically measure the brain. They developed new techniques for measuring the brain, collected an enormous amount of data, and published it all for free. They also collaborated with similar institutions from around to world, to put together a compendium (EBRAINS) of all of the state-of-the-art neuroscience data.