Evidence suggests that a certain degree of clustering and narrowing of research trajectories is occurring, both on the individual and disease levels. Mechanisms of this process include biases in funding, a lack of coordination among funders, the significant funding role of for-profit actors, and lobbying by special interest groups. The implication is that fewer individuals might control the direction of research and certain diseases could garner a disproportionate amount of attention and resources, which could be an epistemic threat to medical progress. In this perspective article, we highlight the scale of the issue, mechanisms underlying this process, and their effects on medical progress. The article also explores potential solutions to counteract an excessive narrowing and clustering, highlighting the importance of individual researchers, patients, research organizations, and funders in ensuring that a sufficiently-diverse set of medical research trajectories are being pursued.