It's far more than that though, your democracy is becoming beholden to it, the rich can lobby while the middle and lower classes can't. Or at least can't as effectively.
The rich can run for office much easier than the middle and lower classes.
The rich can monopolize new markets by simply undercutting new entrants.
I'm sure there's many more examples than this of how by concentrating vast wealth to a few people you cut out opportunities for everyone else.
which predicts that interest groups who have money to gain from a particular policy will fight harder to get their way on that policy than will voters in general who might gain more from a different policy.
In education policy, there is HUGE access to the legislative process (especially at the state level, where most education policy is made) for the schoolteacher labor unions. The general public doesn't get the same kind of place at the table, by far. But politicians are not embarrassed by that. They call special access for special interest groups "taking care to consider the point of view of stakeholders," and don't think about policy in terms of what's right in the abstract, but rather in terms of what's expedient for staying out of political trouble. A quiet majority of inadequately educated Americans struggling to find time for political participation while making ends meet has less voice in the process than a vocal minority of wealthy people whining about "class warfare," and also less voice than a minority of people employed by publicly funded schools who are not held accountable for results.
The rich can run for office much easier than the middle and lower classes.
The rich can monopolize new markets by simply undercutting new entrants.
I'm sure there's many more examples than this of how by concentrating vast wealth to a few people you cut out opportunities for everyone else.