Lightning network seems to tend towards centralization

LN (off-chain):

The tendency to centralization is observable even when considering weighted quantities, as only about 10% (50%) of the nodes hold 80% (99%) of the bitcoins at stake in the BLN (on average, across the entire period). Lin, Primicerio et al. (2020)

(1) https://iopscience.iop.org/article/10.1088/1367-2630/aba062

A clear tendency for new nodes to prefer opening channels with already well-established nodes emerges from the figure. The LN seems that may resemble, therefore, an “hub and spoke” configuration with some extremely well connected and endowed nodes acting as hubs capable to attract and create connections with a great number of other new nodes.

It does not hold however as valiantly as for random failures in case of malicious attacks performed by removing very central nodes with respect to the strength, the eigenvector or the betweenness centralities of its nodes. In addition, the possibility to create the conditions for reaching coordination among its nodes has been shown to be extremely low. Finally, we find contradictory results in the evolution of the anonymity. Martinazzi and Flori (2020)

(2) https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0225966

We quantitatively study for the first time the proneness of the current Lightning Network to the wormhole attack as well as attacks against value privacy and relationship anonymity. We observe that a moderately resourceful adversary controlling only 2% of the total node count can carry out these attacks with high success probability Tikhomirov, Moreno-Sanchez and Maffei (2020)

(3) https://eprint.iacr.org/2020/303.pdf

Bitcoin (on-chain):

Bitcoin achieves this consistency through the use of a peer-to-peer broadcast topology. Every Bitcoin peer initiates a connection to up to eight others, and maintains a maximum of 125 total connections (incoming and outgoing), rejecting any connection request that would push it beyond this capacity. Its total connections constitute that peer’s neighbors

Bitcoin’s peer-to-peer broadcast is based on flooding neighbors’ links in a gossip-like manner. At a high level, when a peer learns of a new transaction or block, it informs its neighbors by sending a INV message containing the item’s hash to each of its neighbors. Miller et al. (2015).

(4) https://www.cs.umd.edu/projects/coinscope/coinscope.pdf

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