Cracking Bitcoin Addresses on AWS

If they are 256 bit hashes then there are approximately 2^256 private keys possible and the author guessed around 2^31 possibilities in 6 months with 0 hits at a cost of $720. I can't do math this big on my phone but it would be at least 10^40 years to get even a first guess, and by that point you've spent more on compute than that first wallet would have in it.