Musk over and over again has shown that if something that he wants is expensive he will invest as much money as required in it to develop and to build it in large quantities. If Musk had thought lidar cost was the big problem, they would be building a lidar giga-factory right now. But they don't because not using lidar wasn't about cost.

He might be right or wrong about that, but he wouldn't just ignore lidar because its currently on on the market cheaply.