It's hard to profit off selling something with no per unit cost associated with copying when buyers have the legal ability to resell. Successful FOSS businesse

It's hard to profit off selling something with no per unit cost associated with copying when buyers have the legal ability to resell. Successful FOSS businesses usually make money off of selling exceptions, (i.e. selling to non-free software companies) or creating a product with per unit cost (e.g. support).