Metcalfe's law states that...
...the financial value or influence of a telecommunications network is proportional to the square of the number of connected users of the system (n2).
From a 2018 paper...
70% of variance in Bitcoin value was explained by applying Metcalfe's law to increases in Bitcoin network size
This means that any network Bitcoin interfaces with, ideally atomically and programmatically, adds value to both Bitcoin's network, and the connecting network's value. Doesn't matter if you personally would use the other network.