The system within which many researchers must work to advance their careers is fundamentally at odds with sharing data. Collecting data is unglamorous, laborious, and often very expensive. This places much data collection firmly within the purview of research institutions, where resources and cheap labor are abundant. To progress in this context, one must publish. It isn't enough only to have collected the data; the researcher must also be the one to analyze it, and to do so before someone else does. Thus for any self-interested person in research, there is no incentive to disclose hard-won data to the public at large, effectively crowd-sourcing analysis and foregoing the career advantages and opportunities that a large store of useful data offers. One may find it unethical, but few who have committed many years of hard labor to advance in a research context would do otherwise.