Let's do the math. An a1.2xlarge reserved instance with the longest available term (3 years) is $672/year, or $3,360 over 5 years.
A bit of browsing on Geekbench suggests that one a1.4xlarge instance (i.e. two a1.2xlarges) is roughly comparable to a Ryzen 3400G. Adding in rough costs for the other components (motherboard, power supply, case, and 32GB of RAM), a bare-metal system equivalent to an a1.4xlarge looks like it would cost maybe $500-600 to buy outright.
In other words, if all you care about is raw CPU performance, then over long periods of time AWS costs more than 10x as much as bare-metal per unit of performance, even with up-front reserved instances.
Except we are talking about a2’s (m6g) brother, the whole point is that the math changes significantly with these new instances. The a1 was not competitive.
A bit of browsing on Geekbench suggests that one a1.4xlarge instance (i.e. two a1.2xlarges) is roughly comparable to a Ryzen 3400G. Adding in rough costs for the other components (motherboard, power supply, case, and 32GB of RAM), a bare-metal system equivalent to an a1.4xlarge looks like it would cost maybe $500-600 to buy outright.
In other words, if all you care about is raw CPU performance, then over long periods of time AWS costs more than 10x as much as bare-metal per unit of performance, even with up-front reserved instances.