A lot of people believe Sanders was cheated by the DNC out of a rightful win. That’s totally unsubstantiated.
I can’t prove Wikileaks is largely directed by Russia — but I can certainly say that their behavior looks that way to me and the statement of the IC say they are — and I believe them.
There is far less evidence for insider-leaking. But: you do you. I case anyone reading wants to look deeper into Wikileaks, here is a handy infographic guide: