I often feel that this is not quite known in the automotive business, but: "Open Source is free as in puppy. It comes with responsibilities." (via https://www.christianheilmann.com/2015/09/30/of-impostor-syndrome-and-running-in-circles-part-3/)
In the meaning that releasing a project open source is as free (money and responsibility wise) as getting a puppet for free (money and responsibility wise). The act doesn't cost you anything so technically it is free, but you get to take care of this creature now, feed it, give it a place to live, tame it so it doesn't crace out, etc.