“For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you by his poverty might become rich.” (2 Cor 8:9)
By his own choice Jesus was not rich. He could have been rich if he had fallen for Satan’s temptation to worship him. He would have become the king of this world. But, as we all know Jesus’ kingdom was somewhere else: My kingdom is not of this world”. Thus, the text says that Jesus “was rich”, and for a split second while contemplating Satan’s offer he was.
Luke seems to rendering Jesus words clearer than Matthew on this issue:
“Blessed are you who are poor, for yours is the kingdom of God. But woe to you who are rich, for you have already received your comfort (Luke 6:20,24).
The Aramaic Bible in Plain English seems to have the correct interpretation of Mat 5:3:
"Blessed by The Spirit are the poor, because theirs is the Kingdom of Heaven."
Jesus also said that we should sell our excess belongings, stuff we can be without, and give to the poor to store up treasures in heaven. If we do this we would follow his (above) example (Luke 18:22)
The other way of tackling the issue in question is, of course, the purely spiritual way. But Jesus was not a trailblazer in this. Thus, it is too common to even contemplate, being repeated every day in every classroom all over the world. Even Jesus was subjected to this by the teachers in the synagogues, when he was young. By teachers, rich in knowledge, lowering themselves down to their subjects’ levels too better teach them stuff.