Ever heard of Second Life? It's basically an online 3D role-playing game where you can make an avatar character and go hang out with others. Zuck wanted to make a Facebook-flavored VR version and marketed it hard to companies as the "future of customer engagement". Zuccboi just happens to have forgotten to check whether people are actually stoked about spending a thousand dollarinos for a VR kit only to spend their time in 3D Facebook Advertisement-Land. So, you know, people who would have been interested stuck to their usual haunts in SL, VRChat etc.

Of course it didn't help that when their actual software came out it had such shitty graphics that it made early 2000s games look photorealistic.