The phrase "the Son of Man has nowhere to lay his head" is found in two places in the New Testament: Matthew 8:20 and Luke 9:58. In Matthew 8:20, Jesus is speaking to a scribe. In Luke 9:58, the scribe is not mentioned. It simply states, "Someone said to Him." In both cases, the Scribe stated, "Teacher, I will follow you wherever you go." That is when Jesus said, "The foxes have holes and the birds of the air have nests, but the Son of Man has nowhere to lay His head." What Jesus meant can have different, but similar interpretations. But basically, it means that His followers can't expect to have a comfortable and easy life.

Have no confidence in earthly things, but in God.

The ministry of Jesus meant He had no permanent home. He had to depend upon the provisions of God the Father through the people of Israel. Jesus wanted those who follow Him to understand what it could cost. Being His disciple means His followers may not have any earthly comfort or stability. Remember, Jesus wasn't married. He had no children. He came to serve the Father who called Him to teach, to sacrifice, and glorify Him. In light of this, the words of Jesus ring true when he says in Luke 14:28, "For which one of you, when he wants to build a tower, does not first sit down and calculate the cost to see if he has enough to complete it?"

Suffering and struggle

The mission of Jesus was more important than personal comfort and provision. His strict dedication to the will of God the Father meant embracing inconvenience, suffering, mockery, and struggle. He was informing the scribe that to follow Him might cost him everything.

Conclusion

Why would this be the case for Jesus and His followers? It is because He came not to be a king, not to receive money and wealth, but to serve and to speak the truth about sin, righteousness, salvation, and judgment. Doing that in a hostile world is dangerous. We know this because they killed Him for it.