GPT would charge more if they could. Both companies need way way more revenue. GPT simply made a calculation that they can earn more money by charging less than their competitors.
They're cutting prices because they want to cannabalize the market for people using models like deepseek via API as well as people paying for anthropic subs.
When they cut prices on luna the first time around they took (literally) millions of users from anthropic.
Any business would charge more if they could. Jevon's paradox would mean that they can make more money by charging less because demand is going to keep growing.
Of course they'd charge more if they could... Of course they're pricing to outcompete their competitor...