I don't know where you're getting this "massively increased hardware and hosting costs" from - we run our trading platform on bog standard x86_64 hardware, as has every other PHP site I've worked on (some even run in VMs with 500MB of memory).
Because you are buying 10 times as many servers, and paying for power for 10 times as many servers. Where on earth did this "bog standard x86_64 hardware" business come from?