Microgrids that enable peer-to-peer energy exchange represent an important enabling technology for scaling renewable energy. Furthermore, peer-to-peer microgrids are an essential ingredient of the swarm electrification approach, facilitating the modular growth of infrastructure for energy access in the developing world. However, peer-to-peer microgrids heavily rely on the initial and continuous participation of users, called prosumers. This work shows how prosumer participation can be achieved and how sustainable microgrid development can be ensured. We identify (a) motivational drivers for potential users to join the microgrid community, (b) measures that can stimulate such motivation, and (c) design criteria for these measures to ensure the sustainability of microgrid development. The results demonstrate that incentives for prosumer participation must extend beyond financial benefits and ensure community-wide access to asset creation. We undertake a bottom-up analysis, from the user perspective, to identify the critical factors for ensuring successful microgrid development. To this end, the analysis includes an exemplary on-site case study with users of solar home systems in Bangladesh. With over five million solar home systems, Bangladesh is the global leader in terms of the number of standalone energy systems installed, and other regions in the Global South are quickly catching up. The proposed measures assessed in this work seek a balance between the goal of increasing user value to encourage initial participation and the goal of sustainable microgrid development. Furthermore, practical experience from applying the proposed measures is discussed. The research presented makes valuable contributions to the understanding and implementation of peer-to-peer microgrids worldwide, particularly for energy access in the developing world.