I'm curious. Why do they keep letting people onto Babylon 5 who have no real reason for being there? Why do they let all those lurkers live below when they don't contribute to the overall mission of the station? Is earth so full they refuse to accept them back?
People don't go there with the intention of being stuck and homeless. They go there for legitimate reasons and then can't afford to leave for whatever reason. The young Telepath girl Alisa Beldon, lived with her dad, who passed away and then she had no one, for instance. Others have a business opportunity and spend everything they have to get there, and then the business deal doesn't work out. Others may simply be Blips running from Psi Corps
As far as sending them back to Earth, Julie Musante says in Voices of Authority "Earth doesn't have a Homeless problem", so Earth isn't likely to take these "degenerates who choose to be poor and homeless" and then of course, the whole situation with the bad blood that develops between Earth and B5
Additionally, not all The Lurkers are from Earth.