Short answer:

Yes, but if you bake-in safeguards you will be much better off than trying to wrestle the power back later.

Long answer:

I would argue that most times they are. Looking at our own government, one would assume that those "in power" can write laws (legislative), enforce laws (executive), and/or interpret laws (judicial). The more of these branches those "in power" have, the more power they have over laws or "the rules." The more of the branches filled with wealthy individuals, the more likely they will exhibit qualities typical of the wealthy. And I believe wealthy people typically fall into two groups: zero sum and non-zero sum. Zero sum assume that money is limited, if one gains, another loses. Non-zero sum assume that working together two people can make more than the sum of their parts, if one gains, another gains. I know none of the ultra wealthy personally, but I am inclined to think more ultra wealthy are "zero sum." Further, these zero sums will likely feel very inclined to protect their status, and keep the poor poor, as a matter of self survival. As such, the more influence the wealthy have over the three ways rules effect us, assuming the typical proportion of zero sum and non-zero sum that I believe exists in the wealthy also exists among the wealthy in power, the more likely the rules will be zero-sum minded, and aimed at keeping the poor poor. Non-zero sum ultra wealthy definitely would not like the idea of high taxes for the ultra wealthy. I think we need look no further than the Tax Bill at the beginning of our current administration to see that non-zero-sum ultra wealthy likely do have a great deal of power and do use it to write the rules.

That said, the three-branches system of government (executive, legislative, and judicial) is a good example of smart people realizing that you can at least bake-in safeguards into a system. Yes, they were wealthy, but nowhere near as wealthy as the ultra wealthy of today, who are more like the royalty wealthy of their time. They certainly did not want any more kings. Their system did a pretty good job for a couple hundred years of splitting power and putting in checks and balances to prevent one person or group taking control of all, or most, branches. Or, centralization-proofing, if you will.

I am no expert in America history. I may be wrong in this. But it seems from my current perspective that this is the longest one group (specifically, non-zero-sum ultra wealthy) have had so much control. That is, other than the two groups that started it all, namely whites and males, and clearly neither of which are mutually exclusive of the non-zero-sum ultra-wealthy group. And like whites and males had, they have put in their own safeguards to keep their power as long as possible. The parties change, but the taxes never really seem to go back to pre-Reagan levels, do they? Will the non-wealthy have to wait as long as women and non-whites to wrestle even a small amount of power towards them?

Arguably, there is still hope. Yes, it seems like there is a wall of money around the branches, through which only those also made of money can pass through. But the wall might not be able to smell the difference between non-zero-sum money and zero-sum money. Maybe that means some non-zero-sum wealthy will slip through and, once inside, tear down the wall. But I suspect while the money-wall can't smell the difference, the money-people inside can, and will thwart the non-zero-sum wealthy, so that may not work. Or maybe the non-zero-sum wealthy will fund tools that can put cracks in the wall of money, allowing non-money people to slip through. But certainly the zero-sum wealthy are funding tools as well, ones that fortify the wall. And, again, there's still the problem of those already in thwarting anyone who slips in.

I have no solutions here for the current situation with the American government. But I do think there's a lesson. Plan well ahead of time, an ounce of prevention is worth a pound of cure. Because once it's too late, and centralization occurs, it seems almost impossible to overcome.