Maybe for a small number of companies in a small number of industries, but most companies rent their office premises, even large companies.
I've worked at several multinational companies that sold their HQ buildings when they recognised that building management was not a core competence for them and tying up capital in real estate has a significant opportunity cost for them.
It's no skin off their noses if commercial real estate plummets in value - if anything, it would be in their favour as their rent would decrease.
Amazon is shitting money. They're not exactly a typical company.