I'll dig up the literature a little later on, but studies on VR motion sickness are picking up steam. One of the VERY interesting conclusions is that it affects women far more than men. Even then, rates for both are quite high, and enough to be an issue for sales. Again, I'll dig up the research and paste it here later, as it is very interesting. Big challenges around how designers plan these titles out, and whether they bother including these audiences or just push forward with more "action" oriented experiences at the expense of losing a percentage of the market that can't consume it.