Because she says so.
https://www.dailywire.com/news/39926/elizabeth-warren-compares-scrutiny-her-native-emily-zanottiApparently, her heritage-related troubles aren't the fault of an incurious family who culturally appropriated indigenous American ancestry without any evidence they were related to a single Native American, but rather the fault of a "right wing" noise machine hellbent on casting Warren as ... something.
Maybe she'll team up with Hillary. Then they can both complain about the vast, right-wing conspiracy.
“They have called Elizabeth ‘Pocahontas’ and used racist depictions of Native American history, culture, and people to make Elizabeth the butt of a joke," the website notes. “These actions not only dishonor Native people and their many contributions to this country, but perpetuate harmful stereotypes that Native communities continue to fight against.”
I still think the people who have trolled her call her "Fauxcahontas," not Pocahontas.And it isn't those people who dishonor Native Americans, it's people like Warren -- who falsely claim to be something they're not. Elizabeth Warren made herself the butt of an on-going joke; nobody had to do that for her.