Yes, it's debatable and I would argue that most ultra-rich people are at least guilty in perpetuating unsustainable model which they inherited.
But people who starts with "rich get richer" are usually not for debates, they adopted simplistic view that rich are the ones to blame, while replacing their iPhones every year and driving 3 tonnes trucks.
Regardless of the motives for pointing it our, either the rich are getting richer or they are not. The evidence appears to supports the former, that the rich, due to a variety of reasons, are indeed getting richer while the working class are stagnating. That is the problem.
This has nothing to do with laying blame or whining, just the fact that the gap is becoming a gulf and does not appear to be sustainable in the long term, perhaps not even in the medium term, ie, the next fifty, sixty or seventy years.