One should definitely not default into "we're secure because we use AWS". But let's be honest, how many servers in the basement feature video surveillance? How many destroy their hard disks securely?
An honest statement would be "we reduced our burden of security by building on top of AWS".
Yeah! The amount of toil and burden AWS removes or reduces for me across the board (security, managed services, running multiple datacentres and everything necessary to do so…) means I can work on vastly more valuable things. Which more than makes up for the price.
The cost of 1 server is not a sufficient metric of value.
Not to counter your point, but what I've learned and was suprised how cheap it is to letting a company destroy your harddisks and USB sticks - at least in Germany.
An honest statement would be "we reduced our burden of security by building on top of AWS".