I think it's clear to most people that Trump fired Comey because he refused to say publicly what he had told the president privately - that Trump himself was not under investigation. Does anyone actually believe Trump conspired with the Russians to alter the results of the election? The claim is utterly ridiculous, no one thought he would win, not even Trump. 
Meuller will investigate, spend lots of taxpayer money and won't find any evidence of collusion. Why? Because it doesn't exist, if it did someone would have leaked it by now. You see what they're doing is selectively leaking classified information that could be construed by opponents as inappropriate (Kushner/Flynn talking with Russians before Trump assumed office), when in reality there were no crimes committed. Their goal is to bog down the administration in conspiracy theories, unproven accusations and non stop controversy - all in the hope of killing Trump's agenda any way they can.