What are you talking about. Hamas is primarily funded by Turkey and Qatar. Both countries with massive US military bases. For four decades we've now been hearing how Iran almost has the nuclear bomb[1], how Iran funds Al-Qaeda, when it fact it's the other way round because Shia's are considered infidels to these people. Various Israeli government officials including Mossad guys have on various times admitted that they propped up Hamas to keep a legitimate government from forming.
Hamas is an offspring of the Muslim Brotherhood. The Egyptian army hates them, the Syrians fought them, Iran fought them. Israel, Turkey and the US all fought on the side of Alqaeda in Syria[2][3].
US shut down Turkey's banking integration with Russia with a simple threat of turning off the tap to their banking system. They could shut down Hamas funding in a heartbeat. But they don't it, why[4]?
[1] https://www.upi.com/Archives/1984/04/24/Ayatollah-bomb-in-pr...
[2] https://wikileaks.org/clinton-emails/emailid/23225
[3] https://www.reuters.com/article/idUSTRE81N1EX/
[4] https://www.timesofisrael.com/mossad-chief-top-general-visit...