The statements about the net worth of the Palestinian leadership are difficult to verify. There is no reliable source that provides accurate information on this topic. Some sources claim that Yasser Arafat's family is worth $1.3 billion, while others put their net worth at a much lower figure. Similarly, there is no consensus on the net worth of Mahmoud Abbas or Khaled Mashal.
It is important to note that these statements are often made by people who are critical of the Palestinian leadership. They may be motivated by a desire to discredit the Palestinian cause or to justify Israel's occupation of the Palestinian territories.
It is also worth noting that the Palestinian leadership is not a monolithic entity. There are many different factions within the Palestinian Authority, and they do not always agree on the best way to achieve peace with Israel. It is therefore possible that some members of the Palestinian leadership are more interested in personal enrichment than in achieving peace.
Ultimately, the truth about the net worth of the Palestinian leadership is unknown. There is no reliable evidence to support the claims that they are all multi-millionaires. However, it is also possible that some members of the leadership have increased significant wealth through corruption or other means.