He's spent time, thought, and money developing software, and people are expecting him to just give it away, and allow others to make money out of it without giving back anything in return? That would be fair only if the companies which use it to increase their profits also open sourced their software.

Before you suggest developers the consultancy route, that penalizes the developers of software which is so well written and documented it can be used straight out of the box.

One thing I'd do differently to him: whenever the user isn't goint to profit from the software financially (in this case, hobbyists and students), there's a good case to be made not to charge for it, as without an initial user base, it will be difficult to sell it to companies. But if he wrote the code, he can decide on its licence.

He doesn't have to open source it/give it away if he doesn't want to, of course, but if he doesn't, his language and tools will probably eventually be surpassed in use by other, more open tools and languages. That's the way language and tool development has been going lately.

That helps to prevent his software from becoming a cash cow, as it encourages constant innovation on his part to stay ahead of the open-source competition. But until the open source replacement is as good, he'll still be able to earn money by licensing it.

The question would be whether open-sourcing now might lead to higher profits over the long term than remaining closed-source until some later date. In the case you suggest, it could be that once the open source replacement is as good --- or nearly as good -- the closed-source business simply shrivels up and dies.

By switching now, before open source has caught up, the currently closed-source company could attract users and grow greatly now, quite possibly preventing the open source options from ever catching up (and at least greatly delaying that).

This, of course, requires a change in the business model, idea would be that revenue is generated differently, probably much less per-user, but with a great growth in users. It's then an open question which option will generate more profit over the long-term, but it is at least not clear to me that open sourcing now -- when product is way ahead of open source alternatives -- is the wrong decision.

I'm unclear about how you suggest people make money after giving their software away for free. I've dealt with consultancy in an earlier post.

The term open-source is ambiguous. It's possible to release the source and still charge for the software and have restrictions on its use or distribution, e.g. by having a shared-source licence.

Use of shared-source would mean anyone intending to release their version of the software on a different licence would not only have to rewrite the code from scratch but, to avoid suspicions of plagiarism, take great care that their code bears no resemblance to the source code, which they have already been given.

Finally, I've already pointed out that requiring payment for commercial also buys the developer time, and encourages them to improve the software or develop entirely new software.