Swarm wasn't a competitor to SpaceX at the time, Swarm and Starlink wasn't aiming at the same market at all. And they didn't exactly kill Swarm. They launched Swarm satellites for a while and there was talk of integrating Swarm transceivers on Starlink satellites. I think once direct-to-cell became a reality, the idea of Swarm was subsumed into that project since it should do everything Swarm did but better. It's worth noting that the Swarm founders are now working on the direct-to-cell project.