This study investigates two paradoxes in high-tech sectors: competition versus cooperation and open-source versus proprietary platform development. Through a longitudinal analysis of Google's TensorFlow platform, we show how open-sourcing can create strategic value despite the loss of intellectual property. While firms give up intellectual property by open-sourcing, they can expand markets, driving demand for complementary products and services. Our findings suggest that companies may need to engage in open-coopetition to protect their market share. Executives face a trade-off between overall market growth potential and safeguarding their market share with intellectual property. Policymakers should understand how open-coopetition can accelerate innovation more inclusively. For developers in the growing artificial intelligence market, open-sourcing is often a competitive necessity rather than a choice. The case of TensorFlow demonstrates that in high-tech sectors, open-sourcing and open-coopetition are strategic imperatives, not just idealistic pursuits.