Just to be clear, I'm not arguing against WFH, just providing possible reasons big companies are against it.

They don't lose that they gain that because they no longer have to pay for a building.

That only applies to companies that rent. If they own the building, then an empty office becomes a waste

The companies that lose out are the ones that decide to do this stupid hybrid system which is literally the worst of both worlds.

I disagree on that one. Not everyone wants to WFH or do it full time. Also if they meet with outside persons regularly, like customers and want to do it in person, having an office is useful. Obviously this does not apply to all companies, but it's wrong to say that the hybrid system is the worst.

The money they spend on the building and maintenance.