Online digital platforms organize and mediate an ever-increasing share of economic and societal activities. Moreover, the opportunities that platform-mediated markets offer not only attract enormous numbers of entrepreneurs but also support the growth of entire ecosystems of producers, sellers, and specialized service providers. The increased economic and business significance of digital platforms has attracted myriad studies exploring their power dynamics and general impact. This research has largely overlooked the power imbalance that entrepreneurs experience as members of the platform ecosystem, and provided little guidance on how these far more numerous firms should compete. Drawing upon power-dependence theory, we show that the power asymmetry in the relationship between the platform and its ecosystem members is intrinsic to the economics and the technological architecture of digital platforms. We conceptually analyze the sources of this power, and we unravel the novel component of risks that emanate from this imbalance. Our analysis suggests that the conditions of engagement for platform entrepreneurs are so different from traditional entrepreneurship that these entrepreneurs are more usefully termed "platform-dependent entrepreneurs" (PDEs). Further, we explore the strategies that PDEs are developing to mitigate their dependence. Finally, our study provides a framework for policy-makers that are considering regulating platform-organized markets.