Matthew was a tax collector when Jesus called him to join and follow. Tax collectors were universally hated because they kept $$ for themselves above and beyond what was due and became rich. When Jesus called him, he got up and followed. The only thing he took with him (it has been said) was his pen. He used it to write the Gospel of Matthew. Could you get up from your job and go off with Jesus for a different life? Why did Matthew? It is obvious in his Gospel as will be explained.