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Google, Netflix, Meta, and Akamai serve content to users from offnet servers in thousands of ISPs. These offnets benefit both services and ISPs, via better performance and reduced interdomain and WAN traffic. We argue that this widespread distribution of servers leads to a concentration of traffic and a previously unacknowledged risk, as many ISPs colocate offnets from multiple providers. This trend contributes to many Internet users likely accessing multiple popular services and fetching the majority of their Internet traffic from a single facility -- perhaps even a single rack -- creating shared resources and a correlated risk in cases of failures, attacks, and overload. Alternate ways to access the services often lack sufficient capacity and share resources with more services, creating the potential for cascading failures.