but only by the group of owners
Bitcoin's technology which is the blockchain isn't owned by any group or individual.
Bitcoin is a decentralized system centered in Blockchain, and this is nothing to manage, everything runs by itself in place, so that all looks transparent in terms of transactions.
True.
But with those working for their projects or business, the distribution of such rewards is centralized.
Distribution of bitcoin/reward to projects or businesses is centralized because the distributor itself or the owner is organized but the whole tech itself is decentralized.