You assume that they hired with eventual plan of firing. Thats not the case. They hired because opportunity cost of not hiring was too high.

They should have known that an economic downturn was possible and planned for it. Wtf do these C-level execs get paid millions of dollars for?

Preparing means potentially missing out on revenue during the time before the downturn, a.k.a the opportunity cost that I mentioned.

They get paid for lining the pockets of shareholders as effectively as possible quarter to quarter

Why the assumption that they didn't plan for it?

I still don't get Google and the others having huge revenue per employee.

Google could easily put these people in making more money.

But instead they launch weird products like their Blockchain service, miss out on AI etc.

Google Io is in May, if they don't announce google personal ai assistant they don't have enough visionary people.

When it comes to increasing revenue, nobody really knows how the userbase is going to adopt a product. Look at Vine vs Tik Tok. Same exact format, but one died and one took off like a rocket ship.

When companies can invest money, they do so without concern for long term in the hopes that they can just bruteforce project with manpower and make something stick. If you don't participate in this, you risk missing out establishing a product that has long term staying power and thus long term revenue.

So it figures that when these costs start running high, things get cut. And when everyone is downsizing, and you don't and instead choose to invest, you risk losing money on a failed product that you could have spent later on something profitable.

Google doesn't need to play the unicorn game.

They have plenty of services to make better or add features like Google cloud.

They can do things like what Ms does: have multiple dominating products and still have no issues with companies using azure.

Google just could disrupt any industry the wish.

They could spend much more on enabling 3th world / emerging countries

Oh, they'll announce it. They just won't ship it. That's I/O for you.