> There was a huge media campaign smear against him (led by the DNC itself)

There is no evidence of the DNC running a smear campaign against Sanders.

> Massive amounts of donations were funneled in ethically questionable manners into the Hillary campaign.

You're presumably referring to the Hillary Victory Fund here. You can see on the donation page (still up: https://www.hillaryclinton.com/donate/go/) that the first $X of contributions goes to the Clinton primary campaign, the next $Y goes to the Clinton general campaign, the next $Z goes to the DNC, and the final money gets distributed to the state committees. The issue wasn't that the money was going into the Clinton campaigns but that it was going to the DNC instead of the state committees. The DNC's excuse was that they were using it to build common campaign infrastructure for use by the state committees.

> People were hired in a black flag op to discredit his supporters.

There is no evidence of a black flag or false flag operation against Sanders.

In summary, there is no evidence that the DNC sabotaged Sanders, yet he still lost by millions of votes, so the claim that he is one of the most well-liked candidates of all time goes against the actual voting data.