For some reason once you start talking about space people stop thinking about it as one of many alternatives. If you want to think about industrializing space, simply being possible isn't enough. The unique challenges of operating in orbit (of which cooling is only the most obvious among a great many problems) need to be addressable efficiently enough that sending it up still makes more sense than building it on the ground.
Microsoft's experiments with underwater data centers serve as a powerful parallel since it has many of the same challenges but is still significantly cheaper. If it were economical to put a data center in orbit it would be even more economical to put it in an underwater container, so if we aren't doing the latter we would need a hell of a good reason to do the former. See also the economic challenges of living on Mars, the moon, or even LEO compared to Antarctica or ocean platforms.
Yep. The broker is effectively buying at $19.80 and still selling to their customer at $20.00. Now, crypto is actually innovative in just how easy this is to do. In fact it's almost required since the transactions are processed in bulk and the miners get to decide what order all the transactions in that block go in. The public mempool also means that even if the miners aren't doing it themselves anyone who wants to front-run basically has a whole conga line of good-faith users (suckers) to get set in front of and identify the most profitable position. Without the miner's privilege you'll need to deal with transaction fees and it's going to be harder to find opportunities, but it's so easy to search that I wouldn't expect it to matter.