Similar people to these geniuses also predicted Airplanes will take millions of years to develop back in 1903...

https://bigthink.com/pessimists-archive/air-space-flight-impossible/

These people are always vastly overconfident for no reason. Maybe if we had to design a computer exactly the same as a brain it would take a hundred years, but we don't, we can use vastly more power than the brain to match its computational power, we can use far larger volumes of computational area since we aren't restricted to a skull and birth canal.

We made airplanes by simply throwing more power and human engineering at the problem, I suspect we'll make AI similarly and if flight was similar AGI will happen within 2 decades, far faster than even 2 average lifespans of hunter gatherers let alone LEV humans...