Transferring huge amount of data between space and earth’s surface is costly and a big bottleneck. If you have a lot of data coming from space (satellite watches and listen to a lot of stuff) that needs processing, you can hit that bottleneck. Moving processing power into space removes it. Data transfer, using any kind of wave (even light) can be make way more efficient, so you can process a massive amount of data way faster, and only send back down there the result.

This has two obvious type of applications : useful for humanity, and dreadful for humanity. Think, doing weather forecast vs. using worldwide pinpoint tracking of any electronic device, including ones that don’t necessarily have wireless capabilities. Guess which one will be prevalent.

Well, that, and doing a pump’n’dump with investors money, since for now the technology to do that reliably isn’t really a thing, and spacex whitepaper just goes “yeah, we know this is a problem, we don’t care”.