Why is most of the innovation happening in software and not hardware?

It feels like most new innovations and startups these days are focused on software-related fields — things like AI, machine learning, and SaaS

Why don’t we see as much visible innovation in areas like mechanical or electrical engineering — for example, in processors, materials, or product design? Why aren’t there as many hardware startups these days?

Is it because hardware innovation is slower or more expensive, or have most of the major breakthroughs already been made?

I’d love to hear your thoughts from an engineering perspective.