These days selling the software itself is rarely successful nor a particularly good business model. Basically only computer games still work like that, and the commercially really successful ones not any more either.

No. You should think in terms of offsetting development cost. When you choose non-copyleft you do it to keep code private, which means you will support all dev costs. It limits how the software can grow because it's basically vertical scalability — not to mention being culturally limited inside the company.

When you choose copyleft you commit to open source and so does everybody who wants a piece of that software, which makes it much easier for everybody interested in it to offset their development through everybody's efforts.

With open source there are documented positive feedback effects. Companies who grow to depend on specific software find it cheaper and more efficient for their own interests and benefit to maintain fewer permanent developers as high upstream as possible — as opposed to having many occasional developers downstream, dealing with stuff as it trickles down.

FOSS creates reliable, diverse and ultimately healthy software ecosystems because everybody competes to improve the software first and foremost.

@WolfLink @poVoq open source is a development model, not a business model, if you don't provide value beyond the bits then you're going to have a hard time but a copyleft license ensures the playing field is level and no vendor can take your code and extend it with added functionality without releasing that code too