I have often wondered if the internet is not so decentralized as we like to think and if that introduces single-point-of-failure like weaknesses to Bitcoin.

This paper seems to find that actually the internet infrastructure can get severely degraded and Bitcoin nodes don't lose much connectivity.

We present the first longitudinal study of Bitcoin's resilience to submarine cable failures, using 11 years of P2P network data (2014--2025) and 68 verified cable fault events.

"the vast majority of inter-country cables must fail before significant node disconnection.""the vast majority of inter-country cables must fail before significant node disconnection."

Because relay bandwidth concentrates in well-connected European countries, TOR adoption increases resilience under current relay geography

87% of historical cable faults caused less than 5% node impact.

I don't know how much if any of the credit for this goes to Core, but my impression is that Core has been highly interested in connectivity and the p2p network created by Bitcoin nodes. Great job!