Fact: Flynn lied to Pence and the FBI about his talks with the Russian Ambassador
Fact: Don Jr and Jared met with a Russian in order to obtain dirt on Clinton
Fact: Campaign manager Manafort had worked for pro-Russian Ukrainian pols.
Fact: Trump asked Russians to find Clinton's emails and they started hacking that very same day
Fact: Roger Stone had some channel to Assange/wikileaks/Russian hackers
Fact: Papadopolous tried to get dirt on Hillary from the Russkies
Fact: Trump was negotiating to build the tallest building in Russia, and lied to the American public about having no business deals going on with Russia
Fact: Russia engaged in a broad conspiracy to get Trump elected and ensure Hillary lost
Fact: after becoming president Trump has been very supportive of Putin, to the extent of stating he believed Putin over his own security agencies
Fact: Trump met with Putin privately and had the transcript from the translator taken away and destroyed
I'm sure there's more, but that's what I recall.
The investigation was to see if there was collusion because there was sure a lot of sparks and smoke and mirrors.