Probably because it was a valid election. There are many aspects you bring up that are either unquantifiable or are merely speculation or innuendo or are just down-right false.
The Russian hacking to help Trump: How much did this actually impact anything? That is a unquantifiable thing. And it is already shown that Trump had nothing to do any of that.
Trump Befriending Putin: That statement sort of goes against the facts that Trump has placed more sanctions against Russia than have been done in the past. He may not be ready to launch nukes at Putin and doesn’t actively antagonize him (in public), but that doesn’t mean he befriended him.
Trump undermining the US intelligence community: Seems like you got that one backward. As time goes by and people actually start looking into the sources of the Trump/Russia investigation, it looks like the US intelligence communities were actively (and illegally) targeting a US citizen AND a presidential candidate (of the party opposite the one in power). Trying to stop that sort of weaponization of the intelligence communities and stopping their illegal activities and trying to hold those performing the illegal acts responsible is not undermining the intelligence communities, it is holding them accountable for illegal acts. As for helping rival countries, I’m at a loss there. He has opened discussions with N. Korea and has stepped out of the Iran Nuclear agreement (that was illegally done, by the way), but those aren’t really “helping rival nations”. Tariffs on China? That isn’t helping a rival country either.