It's not just numbers or speed. It's the shape of the population pyramid. Around the world except Africa, populations are aging. This means less taxes will come in, less workers of prime age, much more healthcare and elder care will be needed, and thus less of the valuable workers in other sectors.

That's only a bad thing if automation and AI don't increase productivity (shrink the number of workers needed). Otherwise, it's a benefit. Taxes are already unsustainable in the US.