Well the Left Wing is ruled by the same class the rules the Right. You want to talk about Oligarchies and the Ruling Class you have to look no further than the Kennedy's
No, it's not. That's ignorance.
Let's talk about the Kennedys, not that an anedotal example of one family proves what hundreds of millions of people are like, as your wrong logic suggests.
You don't even get, obviously, that simply being rich (or poor) does not make a person someone who is out to get all they can for their class - you have Warren Buffets and other rich people who advocate that policies are too good to their class, and you have poor people who fall for right-wing propaganda and advocate policies to let the rich have more of their money.
But on the Kennedys, they are mainly the story of one ambitious man, Joe Kennedy, who was quite talented in making money in a number of industries - from banking where he was the youngest bank president in the country at 25, to the stock market, to the movie industry, to real estate and more.
But what did he do with the wealth? He raised children and taught them the importance of public service, and gave us 3 of the greatest public servants while the fourth, Joe Kennedy Jr., was killed volunteering for dangerous duty after volunteering for three tours of duty as a bomber pilot that was also very dangerous in WWII.
His family did not continue to pursue wealth the way Joe had - the sons each put the money in the trusts appropriate for politicians, and earned a pittance to serve the nation in politics, not to enrich the family. They made real financial sacrifices to do so, just as a figure like Robert McNamara did, at the request of John Kennedy, only months after becoming the President of Ford card company, the first president of the company not named 'Ford'. He could have made a fortune staying in the private sector.
Even Joe Kennedy - after making a lot of money in the stock market under the rules allowed at the time - agreed to shut down the abuses he knew well, and became the nation's first SEC Commissioner and helped put a stop to many of the abuses he had profited from or seen, for the good of the country.
The Kennedys are a great example of the liberals - and Joe Kennedy was only in a very broad sense a liberal, he was really a conservative Democrat in many ways - not using the government to enrich their class the way Republicans use government for the benefit of the rich. A good counterexample is the Bush dynasty, read a book like the one by Kevin Phillips, Nixon's campaign strategist who left the Republican party over the Bushes coming to power as it became a party for the rich.
The Bushes are a much better example of 'crony capitalism', all the way with abusing the governmental power they had for everything from preventing the criminal prosecution of George for insider trading, to moving George to the head of the list for a safe spot in the Texas National Guard, to steering state money corruptly to the guy who got him that spot when he became governor, with the help of a woman (Harriet Miers) he rewarded with top government appointment (and appointment to the Supreme Court), and so on.
I've said many times the Democratic Party has a war between its corporatists and its progressives, so you can find times they do the wrong thing, but that's far from your claim.