If you know what you are doing, it is leaps and bounds cheaper to run your own hardware (co-located, rented from soneone else). The only issue is latency on scaling out (hours), but if you are halfway decent with trend lines you can preempt this.
AWS is not a magical PCI compliance button.
The utter lack of imagination that I see on HN when people are judging others’ technical decisions is kind of hilarious.