Commercial use of copyleft works

Commercial advantage of copyleft works differs from traditional commercial advantage of Intellectual Property Rights (IPR). The economic focus tends to be on monetizing other scarcities, complimentary goods rather than the free content itself. One way to make money with copylefted works is to sell consultancy and support for users of a copylefted work. Generally, financial profit is expected to be much lower in a "copyleft" business than in a business using proprietary works. Another way is to use the copylefted work as a commodity tool or component to provide a service or product. Android phones, for example, are based on the Linux kernel. Firms with proprietary products can make money by exclusive sales, by single and transferable ownership, and litigation rights over the work.
Internal use.
Businesses and governments can obtain value and cut costs by using copyleft software internally. See for example Linux adoption.
Development.
By building on existing free software, businesses can reduce their development costs. With software that is copyleft, the business will then have the disadvantage that selling licences is rarely possible (because anyone can distribute copies at no cost), but the business will have the advantage that their competitors can't incorporate that improved version into a product and then distribute it without that competitor also making "their" modifications available to the original distributor, thereby avoiding a type of free rider problem.
Copyleft enables volunteer programmers and organizations to feel involved and contribute to software and feel confident any future derivatives will remain accessible to them, and that their contributions are part of a larger goal, like developing the kernel of an operating system (OS). Copylefting software makes clear the intent of never abusing or hiding any knowledge that is contributed. Copyleft also ensures that all contributing programmers and companies cannot fork proprietary versions to create an advantage over another.
The argument for investments in research and development for copyleft businesses may seem weak, by not having exclusivity over the profits gained from the result. Economically, copyleft is considered the only mechanism able to compete with monopolistic firms that rely on financial exploitation of copyright, trademark and patent laws.
Distribution.
Commercial distributors of Linux-based systems (like Red Hat and Mandriva) might have had some ups and downs in finding a successful construction (or business model) for setting up such businesses, but in time it was shown to be possible to base a business on a commercial service surrounding a copylefted creation. One well-known example is Mandrake, which was one of the first companies to succeed on the stock market after the implosion of large parts of the IT market in the early 21st century. They also had success in convincing government bodies to switch to their flavor of Linux.
However, excluding some notable exceptions like the Debian Project (which is expressly noncommercial and committed to free software on principle), most Linux distributors don't actively seek to limit their usage of proprietary software or restrict the proliferation of non-free licenses in connection with their distributions. There appears to be no real reason why an exploitation of commercial services surrounding copylefted creations would not be possible in small-scale business, which as a business concept is no more complex than making money with a "public domain" recipe for brewing coffee—successfully exploited by so many cafeteria owners. However, there are few examples so far of SMEs having risked such a leap for their core business. UserLinux, a project set up by Bruce Perens, supports the emergence of such small-scale business based on "free software", that is, copylefted or otherwise freely licensed computer programs. The "UserLinux" website showcased some case studies and success stories of such businesses.
Art.
In art, making commercial services out of a copylefted creation is more difficult to do in practice than in software development. Public performances could be considered as one of a few possibilities of providing such "services".
The music industry objected to peer-to-peer file exchanging software, but the Electronic Frontier Foundation (EFF) gave some suggestions to resolve the issue.
Objections to the appropriation of ideas for commerce believe intellectual works should not be compared to material property. Giving someone a physical object results in lost possession and control of that thing and can require asking for something in return, payment or barter. But when someone gives an idea to someone, they lose nothing, and need not ask for anything in return.
Often copylefted artistic creations can be seen to have a (supporting) publicity function, promoting other, more traditionally copyrighted creations by the same artist(s). Artists sticking to an uncompromising copylefting of the whole of their artistic output, could, in addition to services and consultancy, revert to some sort of patronage (sometimes considered as limiting artistic freedom), or to other sources of income, not related to their artistic production (and so mostly limiting the time they can devote to artistic creation too). The least that can be said is that copylefting in art tends toward keeping the art thus produced as much as possible out of the commercial arena—which is considered as an intrinsic positive goal by some.
Some artists, such as Girl Talk and Nine Inch Nails, use copyleft licenses such as the Creative Commons Attribution-NonCommercial-ShareAlike license that don't allow commercial use. In this way they can choose to sell their creations without having to compete with others selling copies of the same works. However, some argue that the Attribution-NonCommercialShareAlike license is not a true copyleft.
Where copylefted art has a large audience of modest means or a small audience of considerable wealth, the act of releasing the art may be offered for sale. See Street Performer Protocol. This approach can be used for the release of new works, or can be used for the conversion of proprietary works to copylefted works. See Blender.