I think the two business arguments for open source are:
Open sourcing software assists in its stability by creating a larger user base (users who report bugs) and attracting contributors (free development).
At the same time, open source contributions can promote a favorable view of the company as giving back to the community from which they presumably take. This can be attractive to prospective employees. I've been fortunate enough to be able to work on open source projects and indeed contribute them back to the open source community, and I likely would not be interested in any position where that were not the case to some extent.
Of course, there is always a need for a lot of software to remain proprietary. But at the same time, there are plenty of cases where the benefits of the open source community (testing and contributions) outweigh the risks of helping your competitors (open source generally useful tools, not specific competitive advantages in your industry).
Open sourcing software assists in its stability by creating a larger user base (users who report bugs) and attracting contributors (free development).
At the same time, open source contributions can promote a favorable view of the company as giving back to the community from which they presumably take. This can be attractive to prospective employees. I've been fortunate enough to be able to work on open source projects and indeed contribute them back to the open source community, and I likely would not be interested in any position where that were not the case to some extent.
Of course, there is always a need for a lot of software to remain proprietary. But at the same time, there are plenty of cases where the benefits of the open source community (testing and contributions) outweigh the risks of helping your competitors (open source generally useful tools, not specific competitive advantages in your industry).