You're confusing concentration of wealth with centralization. Concentration is not centralization.

Of course this is centralization, centralization is having very few people having a lot of power over the system.
If that is a large stakeholder via a consensus node (PoS), a large stakeholder voting "his kind" into power (DPoS) or a large mining pool (PoW). All of these things undermine the principle of decentralization.

And as I mentioned PoW, all types of blockchain have similar issues.

If you'd read the literature, you'd know that all these blockchains are heavily criticized for these points. Because all of these blockchain allege decentralization, but in practice it's more a buzzword than real decentralization. (Minings pools, monopolization, etc)

And as I said, I trust a big pool of large stakeholders -> Yes
I trust 1-2 stakeholders -> No.

It is called single point of failure.

And I don't trust a single point of failure, if its a stakeholder or not.