Jesus didnt discourage them however he wanted to point out to them the degree of commitment they should have if they were planning to follow him.he pointed out that they have to leave everything behind and only live the life that God wanted them to live.he tells them the son of man has nowhere to lay his head ....Jesus didnt have any worldly possesions....

there is also  a hint to something else in this paragraph ,thats when Jesus tells them leave the dead to bury their own....pointing out to the fact that all are spiritually dead ....unless they follow Jesus/God