Well, improving your customer experience might actually enhance your ability to make money, at least in theory. But it’s difficult to properly calculate or predict. It requires you to care about your customer experience from a personal standpoint (how do I make my customer happier) rather than just financial (how do I make my customer spend more money). Of course, happier customers tend to spend more, but again, difficult to calculate/predict, even more if you don’t care about them.
Also, with today’s technology (virtualization, containers, microservices, etc), provisioning for spikes is much easier than it was years ago. It could easily be done by Valve with little significant investment, but you know, they don’t care if your experience is bad in events like this, as long as you come back to spend your money later.