If you sell the tool, you're in a race against the model. But if you sell the work, every improvement in the model makes your service faster, cheaper, and harder to compete with. A company might spend $10K a year for QuickBooks and $120K on an accountant to close the books. The next legendary company will just close the books.
For Musk, the move signals an end to his longtime portrayal of FSD as an " appreciating asset," worth buying outright now because the price will only rise as the software improves. And for Tesla, the change represents the latest decision by a tech giant to move towards a software-as-a-service (SaaS) model, in which a provider continues to host its software-handling updates, security, and maintenance-while renting it to users.