There's a meaningful difference between centralized, decentralized, and distributed. I think you may be confusing the latter two.
Decentralized systems can still form groups and have various hubs. In such a case, the security of the network depends on how large these hubs get, not whether they exist at all.
Distributed systems ensure that most nodes are similarly sized and have similar connectivity to the network. In the case of cryptocurrency, many people imagine this as every user of the currency having a roughly equal stake in maintaining and securing the network.
Distributed systems may be ideal for some applications, but they are (likely and thus-far) not required for Bitcoin.
First, the degree of centralization is still relatively low. Individual miners remain small fractions of the network. Some mining pools have gotten quite large in the past, but miners can join and leave pools as they see fit. The risk they present is fairly limited as their network power is not controlled by a single entity.
There's also the issue of geographical centralization. This may be largely the result of ASIC development. Right now, mining profitability relies on rapidly adopting new, more efficient miners as quickly as possible. It strongly favors cheap power and short timelines. As the ASIC market matures and runs into the same hard limits that CPU manufacturing is faced with, the economics change such that more capital investment can make sense. In these cases, mining may be profitable in more geographically diverse areas.
Decentralized systems can still form groups and have various hubs. In such a case, the security of the network depends on how large these hubs get, not whether they exist at all.
Distributed systems ensure that most nodes are similarly sized and have similar connectivity to the network. In the case of cryptocurrency, many people imagine this as every user of the currency having a roughly equal stake in maintaining and securing the network.
Distributed systems may be ideal for some applications, but they are (likely and thus-far) not required for Bitcoin.
First, the degree of centralization is still relatively low. Individual miners remain small fractions of the network. Some mining pools have gotten quite large in the past, but miners can join and leave pools as they see fit. The risk they present is fairly limited as their network power is not controlled by a single entity.
There's also the issue of geographical centralization. This may be largely the result of ASIC development. Right now, mining profitability relies on rapidly adopting new, more efficient miners as quickly as possible. It strongly favors cheap power and short timelines. As the ASIC market matures and runs into the same hard limits that CPU manufacturing is faced with, the economics change such that more capital investment can make sense. In these cases, mining may be profitable in more geographically diverse areas.