My friend Ralph works to further the Eclipse ecosystem in Europe. He argues a lot on the business side of things, and one of the stories he tells in his dog and pony show is how a big company had a large investment in some particular development tools. The supplier of these tools was then acquired by a competitor, who understandably had no interest in supporting those tools. The only way forward for the company was to convert their development process to new tooling, because they couldn't get bugfixes etc. anymore.
The same thing happens when you buy DRM-encumbered media. You effectively give up control of the media to the company you buy them from. Let me illustrate: the new car I bought last year comes with a great feature: the audio system has a USB port where you can plug in a stick with MP3s. I quickly put all of my music on and now I'm sometimes embarassed by the crap I used to listen to in the eighties. The point is: my CD collection goes back to around 1983. I can carry that music forward with me as far as I like because I have it in a reasonably open format. If you buy media that are DRM-infested, the seller still controls it. Just remember when Microsoft pulled the approval servers for it's "Plays for sure" scheme.
The point here is: if, as a company, you rely on some critical piece of software, it really makes good business sense to go with open source software. If you rely on closed source software for a critical piece of your infrastructure, you have just outsourced control over a critical piece of your business to someone else. With open source software, you always have the option to take control of the code yourself. Chances are, you're not the only one relying on the product, so the chance of continuing the development over a long period in time is much higher.