"Blessed are the poor" probably reflects the self-identification of the Jesus community rather than an economically deprived segment of it. The Jerusalem apostles asked Paul to "remember the poor" (Gal. 2:10--i. e. the Jerusalem church as a whole, not just the poor within it, and Paul complied by raising a large collection from his Gentile churches. That is the view of many NT scholars. Why?
The label "Christian" is first applied by outsiders at Antioch. Apart from that, Jesus followers are labelled 'Nazarenes," "the Way" (Acts 9:2; 19:8, 23), and the Poor, better known as "the Ebionites (from the Hebrew ebionim," which means "the poor.") This early Christian movement was probably given their name by Jesus because His greatest pool of followers came from the poor. The label probably stuck because the early Jerusalem church was forced to live as a shared commune, because of all the transplanted Galileans who migrated to Jerusalem without jobs to be part of the Jerusalem church. In the early 2nd century one of "the poor" wrote a Jewish Christian Gospel, called the Gospel of the Poor ("Ebionites"), which has survived only in fragments.
Many of the later Ebionites rejected the divinity and virgin birth of Jesus and instead revered Him as "The Prophet like Moses" prophesied in Deut.18:15-20. They believed that Jesus was "adopted" as God's son by His baptism. As vegetarians, they taught that Jesus rejected all animal sacrifices and they rejected Jesus' substitutionary atoning sacrifice. So they considered Paul "the enemy." Instead they insisted that Jesus died as a martyr to move Israel to repentance. Dismissed as heretics by other Christians and Jews, they died out by the end of the 4th century.