It is not true that every node is an exit node in I2P. The I2P protocol does not officially have exit nodes—all I2P communication terminates at some node within the I2P network, encrypted end-to-end. It is possible to run a local proxy server and make it accessible to other users as an I2P service, creating an “exit node” of sorts, but this is something that must be set up deliberately; it’s not the default or recommended configuration. Users would need to select a specific I2P proxy service (exit node) to forward non-I2P traffic through and configure their browser (or other network-based programs) to use it.