Facebook bought Oculus for 2 billion, and what were they buying there? Oculus had a prototype cobbled together using off the shelf parts by a teenager in his garage, a successful kickstarter campaign, and John Carmack jumped on board.

And that made Oculus worth two thousand million dollars to Zuckerberg.

The acquisition sent a strong signal, though. Shortly afterwards a bevy of competitors, big and small, started throwing out offerings.

Maybe signalling is the only reason to make these outrageous investments. Google thinks AR is important, a massive bid on an early frontrunner can kickstart an arms race which generates talent and knowledge, and even if ML fails, so long as AR in general succeeds, a consumer tech company such as Google will be able to benefit from it.