First of all, if there was any shred of evidence it would have been paraded by both intelligence and FBI. Instead, all we have is just a bunch of hot air coming from establishment shills.
Second, where were all the investigations about collusion between Obama and Saudi Arabia (terrorist country whose Al-Qaeda killed thousands of American citizens)? Or Bush and Israel (country that spied on US)?
it seem hypocritical to claim that Trump's hypothetical ties to Russia are a threat, even if Russia itself wasn't as hostile as some nations with which previous administrations were openly colluding.