I was going to say, I get the sentiment, but it’s incredibly ironic that it’s coming from an American.

Not really. Most people (Americans and non-Americans) make this mistake of stereotyping national populations based on outcomes which not only reduces 49:51 splits into 0:100, but also ignores that sometimes sentiments take time to translate into actions and sometimes the ways they translate are not 1 to 1.

It's a very common viewpoint in America. Trump/conservatives ran on "drain the swamp" and by telling lower and lower middle class people that he was going to bring back jobs to America. Liberals have been campaigning on income inequality (taxes on the wealthy, debt forgiveness for the poor and middle class). The overall sentiment against income inequality is very popular here across the board. The negative attitude toward those who just inherit money is very popular here. Both parties succeed by saying they are going to unseat the most powerful and give the poor a leg up. It's just that both parties have failed to actually do that and their debates between each other about how to do that often lead to gridlock. Arguably the wealthy have succeeded in getting people to nitpick about the way to solve the problem in a way that often avoids anything getting done.

they have more inequality than a lot of countries with royals and nobles (Saudi included I believe).

That's not a measure of the topic at hand though. With inheritance, we're talking about wealth that continues indefinitely despite the person receiving the wealth perhaps doing nothing to actually create it. That's a viewpoint that's compatible with a person doing something today that makes them very wealthy relative to the population. A large reason why the US has the wealth inequality that it does isn't the dynasties, it's that we generate a lot of the wealthiest people in the world. The top 8 richest people in the world are all in the US and all created that wealth over the past few decades as adults rather than inheriting it. And I'm sure you are aware that as you go down the list there are more like Buffet, Ballmer, Gates, etc. that are the same. Not to mention other major non-hereditary creators of wealth like Hollywood or our music industry. That's completely compatible with the viewpoint in the comment that you are referring to. In other words the viewpoint isn't "wealth is bad" or even "wealth inequality is bad". It's "generational wealth so big that it creates virtual monarchies is bad". That's a view that's compatible with thinking it's good for billionaires to be emerging every day, which is a view some Americans have and others don't. It's a view that compatible with thinking that it's okay for some people to get very very rich based on what they do in their life.

It also is a viewpoint that can exist along with a strong belief in an inheritance tax or even just with a general moral support of things like the giving pledge in which billionaires like Bill Gates, Warren Buffet, Elon Musk, Sam Altman, Larry Ellison, Jeff & Marieke Rothschild, Sheryl Sandberg, Michael Bloomberg, Paul Allen, Melinda Gates, Barron Hilton, Carl Icahn, etc. pledge to give "the majority of their wealth to charitable causes in their lifetime or wills."

It’s looking more and more likely that they’re going to end up with the most powerful oligarchy sooner rather than later too.

It is indeed a careful time to watch for that. But that's all the more reason why it's NOT ironic that it's a value that many Americans are pointing to and elevating right now. BECAUSE of our current situation, it's all the more common that people are pointing to this as a fundamental American value to protect which has and should separate us from turning into the kinds of monarchies we separated ourselves from.