You are not wrong, but the practical reality of local hardware is to be batch-constrained in comparison with a multi-user inference cloud. You will never be able to compete cost effectively in your home lab with a cloud that has >100M end users streaming millions of inference requests per second across a gigantic fleet of machines.

Can I run a few inferences in parallel on my Mac Mini? Yes. But put 1,000 Mac Minis in a datacenter serving 1,000 copies of myself? That's going to be more efficient.