The entire US election system is comically insecure and the thing that's surprising is how rare evidence of large scale fraud is. This is probably because it is much easier (and legal!) for rich people to just funnel money into super PACs, buy their own media outlet and/or use political activist "non-profit charities" as tax dodges and jobs programs for their kids.
Why make illegal donations to politicians or outright steal an election when you can just spend an unlimited amount of money on propaganda to brainwash people into supporting your agenda that is completely contrary to their own interests, the interests of their friends and family and their interests of their community? Why would you break the law when you could accomplish the exact same goal legally and get out of paying your fair share of taxes at the same time?