Yes, it is a conspiracy theory: How could it be anything else? You think the Russian government hacked the DNC’s email server to release real Clinton emails proving she was unfit to be President of the USA? Why would Vladimir Putin do such a public-spirited service to the American people?
On the other hand a DNC insider disgruntled by Clinton’s sabotaging of Bernie Sanders’ campaign has very believable motives for releasing the same emails. Occam’s razor says the simplest explanation that explains the known facts is most likely true. The Russian Hackers conspiracy theory is as complicated as an Austin Powers plot, and just as unlikely. In spite of the FBI investigation there has been no evidence found of Russian involvement in hacking the DNC Server, and plenty to suggest a 14 year old amateur hacker could have done so.