You've got the right church, but the wrong pew. McConnell HAS benefited financially from his position of power, but he is nowhere near the richest man in Kentucky. THAT guy is named B. Wayne Hughes, the founder of Public Storage, the largest self-storage company in the United States. He is worth $2.7 billion, according to the most recent issue of Forbes.
Mitch McConnell's net worth is "only" $27 million, which makes him the 11th richest man in the Senate.
The bulk of his fortune is due to the fact that he "married well". He married Elaine Chao in 1993. After her mother died in 2007, McConnell received a tax-exempt money market fund valued between $5 million and $25 million as a gift from "a filers relative."
How he benefited financially from his position of power is highlighted from this paragraph in the Wikipedia article about him:
On January 2, 2013, the Public Campaign Action Fund, a liberal nonprofit group that backs stronger campaign finance regulation, released a report highlighting eight instances from McConnell's political career in which a vote or a blocked vote (filibuster), coincided with an influx of campaign contributions to McConnell's campaign.
In 2015, Time magazine labeled him one of the 100 most influential people in the world, even though he was the ONLY senator that year who had a negative approval rating. The negative rating came roughly a year after he was re-elected to his 6th term of office.
Although he initially supported Rand Paul in the 2016 presidential race, he switched his support to Trump on May 4, 2016. With regard to the US response to intelligence findings that Russia was responsible for cyberattacks undertaken to influence the American election, after Trump won the election, Senator McConnell expressed "support for investigating American intelligence findings that Moscow intervened."Prior to the election, however, when FBI Director James Comey, Secretary of Homeland Security Jeh Johnson and other officials met with the leadership of both parties to make the case for a bipartisan statement warning Russia that such actions would not be tolerated, "McConnell raised doubts about the underlying intelligence and made clear to the administration that he would consider any effort by the White House to challenge the Russians publicly an act of partisan politics," The Washington Post reported, citing accounts of several unnamed officials.
Since Trump values loyalty over everything else, he nominated Elaine Chao to be the Secretary of Transportation shortly after the 2016 election, and she took office on January 31, 2017.
In November 2017, McConnell was opposed to passing legislation to protect Special Counsel Robert Mueller's investigation into Russian interference in the 2016 election. In April 2018, less than 24 hours after an FBI raid on Michael Cohen's (President Trump's personal attorney) office, and after Trump had said that "many people" had asked him to fire Mueller, McConnell reiterated that he opposed any legislation to protect Mueller's investigation. Later that month, McConnell thwarted a bipartisan legislative effort to protect Mueller's investigation.
In November 2018, McConnell told reporters that legislation protecting Mueller was unnecessary and a bill by Jeff Flake would not come up in the Senate since Mueller was "not under threat", citing President Trump as having repeatedly stated the investigation would be allowed to finish. McConnell opined that he could not imagine Trump dismissing the investigation and told reporters they were "trying to get me to speculate about things that I'm confident are not going to happen."
Apparently McConnell does not read newspapers. If he had, he would have read an April 2018 article in the New York Times that published the fact that Trump had to tried to fire Mueller in June of 2017 and December of 2017:
There are still a "few shoes that are going to drop" in the Mueller investigation, and they are Donald Jr., Jared Kuchner, and Ivanka. Once the dust settles on those items, it is not inconceivable that McConnell himself could face charges himself for obstructing justice.