Not sure what the defintion of a psycopath is.
Is it someone who continually murders ? If it is then Jeremy is not one.
If Jeremy did commit the crime, it was simply for money, staus & power. Things he did not have but craved. The five people were in the way & removable in a way where he could avoid blame. The fact that he did not like or respect these people made it easier.
Once he had what he wanted, there would be no need or urge for any more murders.