A: When someone normally sells a sheet, they set their sheet to anyone with the link. What OnlySheets allows you to do, is keep that restricted. OnlySheets will add each new buyer as a viewer to the sheet. Each time someone buys your sheet only they have access to the original.

Yes someone can, and should copy the sheet to their own google drive. But then they can't share the link of the original to anyone else. Well they could but it would be restricted.

A sheet seller usually can keep their own brand protected by updating often, and even making sure their branding is all over sheet not for if people share it, but when they do.