Well, it's essentially wrong.
Others have written better about it than I have, but I did do some online "research" on this about a year ago for my very small readership and I tried to summarize what I learned.
As far as I can tell based on data and analyses published by others, (a) Bitcoin's wealth distribution isn't actually that bad, and (b) the trend lines in Bitcoin are the exact opposite of what has been happening with fiat.
In the fiat system, the "rich" (top 0.1%) have been getting a bigger and bigger slice of the pie, and the share held by the bottom 90% has been getting smaller and smaller.
Meanwhile, in the Bitcoin system, the whales have been gradually dwindling down their share of total supply, while both "retail" and the "public" at large (exchanges, ETFs, and public companies) have been growing their share of total supply.
[See the two graphs in my summary.]
Analogous to other criticisms of Bitcoin, it's easy to criticize the new system for issues inherent in being new (still growing into its future role). But look at the trend and the difference is clear as day.