The actual cost to OpenAI is likely much less. The number in the article is calculating the API cost that a fully maxed out subscription would incur theoretically. The API token cost, however, is far above the actual computational cost.

To make a fresh install less painful: Most applications save all user data in your home folder under .config and .local. Some others make their own .folders, which you can see pressing ctrl+h (for hidden) in your file explorer. You might save these and carry them over whenever you wipe your OS. If you save a list of installed packages from your package manager as well, you can get up and running in just a few minutes on a fresh install.