Skepticism of the claims of law enforcement and the intelligence community are good, for a multitude of reasons, but the case here is a lot stronger than you're suggesting and is substantiated by much more than mere finger-pointing by the US government or other governments.
It's unfortunate that the political climate in the US is on such a knife's edge right now that basically no one trusts anyone and everyone is running with their own databases of the facts of the world.
I understand the US government is itself very largely to blame for this deep distrust, but posts like yours make me worried for the next few decades. This isn't a criticism of you at all, but just general concern that things are kind of coming apart at the seams societally. I really hope the "two movies on one screen" phenomenon doesn't escalate to the point that the screen shatters into a billion pieces.
Sorry, but "high degree of confidence" is not proof, especially not from the organization that told us Iraq had WMDs with high degrees of confidence.
Additionally, at no point in time did they have access to the hardware.
Are you forgetting that this is the same collection of people responsible for being unable to secure their own hacking tools?