In this case the innovators do not benefit more than any one else not investing into the public good, thus free-riding occurs.
While the result of the investment is equally available to all, the innovators benefit through the process of creating the public good.
[2][3] A laboratory study[4] traced the initiation of private-collective innovation to the first decision to share knowledge in a two-person game with multiple equilibria.
It conducted a simulation study that elucidates how inequality aversion, reciprocity, and fairness affect the underlying conditions that lead to the initiation of Private-collective innovation.
[6] The authors argue that the investment in orphan exclusion rights for technology serves as a subtle coordination mechanism against alternative proprietary solutions.
And it is non-excludable because FLOSS licenses enable everyone to use, change and redistribute the software without any restriction.