Did individual developers actually pay that? I’ve done quite a bit of development in the MS ecosystem and can’t recall anyone personally paying for MSDN. It was always through their employer that they got access.
It was priced and designed for companies to be buying as a bundle with other licensing. individual devs would frequently use some of the loopholes through licensing partners to commit to what was basically a three year subscription that spread the cost. For companies, it could mitigate some of the costs associated with the proliferation of environments that needed to be licensed from top-to-bottom. Later, these may stop being eligible for MSDN use and generate more revenue. License auditing was real and gave visibility into this usage.
VMware still have a program like this going for their admin user base. It gets recommended by the r/homelab folks who haven't adopted Proxmox.