How OSS helps companies to save money

Yet another money saving aspect of Open Source Software for companies results from the fact that by open-sourcing their software, many developers (hobbyists but also professionals) work with its code and get familiar with it. So the numer of people that know the specific software code rises. Now, if any company that uses OSS needs to customize or evolve this software it don't depend on just a few and therefore very expensive experts but can choose from a lage pool of OSS enthusiasts. And these people are already acquainted with this software and don't need any time (=money) to get familiar with the code base. However this decreases software development costs and therefore facilitates the software development as such.