> If what you say is true, then subscriptions would get cheaper as more people subscribe, but that's not the case. They just pocket the profit.

The OP’s point could have been better phrased by stating that subscriptions provide an ongoing incentive for companies to support products to minimise churn. Yes they’ll extract almost 100% margin on recurring customers but it’s better than the alternative of one off payment structures where the company is incentived to minimise ongoing costs to the extent they can avoid legal troubles.

If you made a one off payment to a newspaper they’d be incentivised to write low cost articles forevermore because they’ll never get any more money out if you. If you make a one off payment for an OS there’s little incentive to bother with security fixes short of again litigation.