I think to answer your question, yes, the company absolutely should have an infrastructure that can support this kind of load. The product that RH is selling is execution of trades, and failure to do so has drastic consequences. They are not some social network that can afford to go offline for a few hours due to high traffic, the stakes are significantly different.

Another thing to consider is that there are so many great alternatives to RH that were online, despite encountering similar load. If the whole stock trading network went down that would be a different conversation, but users of other platforms were able to trade, and thus RH not being able to provide the infrastructure to handle the load is a huge disservice to its customers.