This guy has been pretty strategic. He has done his research on so many levels. He should know about the capabilities of DNA - particularly familial forensic DNA. There is likely alot of DNA available to police, but it might take time to identify him - they need to parse out out fake DNA samples the killer may have planted on his route (he is playing with everyone with the bullet inscriptions and Monopoly money, why not despose of coffee cups and water bottles, not his, along the way), all the various DNA profiles at the hostel and any limitations on DNA matching available with regards to familial DNA given his potential ethic background (as we know certain ethic backgrounds are less represented in these dna/geneological databases - I know first hand as tracing my husband's history, who is of middle eastern dissent, has been challenging).
I think he is so committed to his cause (this crime took huge endeavor on his part) - exposing UHC for their failure he sees to provide care and being a monopoly that he is willing to die for this cause. He doesn't want to get caught, but given the commitment he has given this, he will die for it. Ever day he isn't caught he is reveling in.
Of course, would love your thoughts.