I did the math a while back, don't have the notes at the moment, but scaling an AWS system I built enough to collect 600m points of data each minute and compute on data within 100ms and retain it for a few minutes would run a bit over $10k usd/mo to operate. I operated it at about 3m events/min with a good amount of compute per including ip to geo lookup... Zookeeper would be the only bottleneck in this case assuming…
Using AWS is the problem here, and that's why it's so expensive. You could do this on bare metal WAY faster and more efficiently, and then you own the hardware forever, for the price you paid to do it for a month with a third party. AWS does not scale this way, you can't just throw more resources at a problem and expect to be profitable.
Cheaper than both and hardly any maintenance required.