Democrats aren't attacking Jill Stein because they think she is taking votes from Kamala Harris. No one I know who's voting Green would consider a vote for Harris at this point. They're attacking Jill Stein because they don't want voters to know that there can be a worker-centered party to the left of the Democrats that supports popular policies like Medicare for All, a $25 wage and federally guaranteed housing.
There are 80+ million eligible voters who don't vote at all because they don't see the point. Democrats are okay with this, in fact, they don't want any candidate to their left to appeal to those voters with popular policies.
The fact that the Green Party exists shows that the Democrats aren't pushing the most progressive policies. Jill Stein's candidacy shows that it's possible to support reproductive justice AND be against funding and arming a genocide. That we can end homelessness if we stopped funding endless wars around the globe.
Democrats don't want anyone to the left of them to exist because it's the only way they can convince Americans that Dem policies are "the best that we can do". To Dems, anything else is just "asking for a pony".
Don't fall for it. Despite Dem's desire to have you think otherwise, things don't have to be this way.
Another world is possible.
"The most educated presidential candidate in history"...? Really? Are you forgetting Ben Carson then? Or is she the 'most educated' because of her undergrad work? (Oh, wait, almost everyone does undergrad work before they go to medical school.) Did you forget that Bill Clinton was a Rhodes Scholar? Or that Barack Obama was a law professor as well as being a civil rights attorney and specializing in constitutional law?
Given that Stein's own campaign has said they can't win, but that they can prevent Harris from winning, it's pretty clear that she knows exactly what she's doing. The only 3rd party candidate that has had a snowball's chance in hell of winning in the last 75 years has been H. Ross Perot.