The same math is there too. They can afford to loose one third of new subscribers to get the same amount of money.

But their new customer acquisition cost wont get higher at the same pace and they get more valuable customers whose payback period will be shorter.

Also i dont think its relevant here, but less customers means less operating costs, so they will most likelly save some money on customer service and behind the scenes things like server upkeeps etc., but i dont think these make real difference here.

Also if for some reason things start to go bad they still have option to create “a budget version” for the people who see the normal subscrition as too expencive.