I thought AHC transfers were very difficult to get chargebacks on. How much could they actually be losing on these events? Are they actually not that rare?
The ACH system in the US is rough. It operates on the theory of "success in absence of failure/chargeback." In most cases, this is fine. You use ACH to pay your rent but charge back? You get evicted. Use ACH for your mobile phone bill and charge back? Your phone gets shut off.
With easily transferrable assets it gets tough. The charge back window is on the order of 30+ days.
You buy BTC via ACH at $X and a week later it's $X/2? Chargeback "I was hacked!". You can fight it as the merchant, but it takes time, tons of documentation, and dealing with traditional bank compliance departments that a) don't know what BTC is or are trained to distrust it, b) are trained to protect their customers, c) are overworked, and d) have no vested interest in resolving it correctly irrespective of evidence.
They are pretty easy to chargeback as long as you initiate it within 30 days of your first transfer. Give a notarized letter to your bank stating that you did not do these ACH transfers to this "Coin Base" company.
You can get ACH charged back for up to 180 days with more involved procedure.
Terminate, yes. Report you to the police, not sure.
Chargebacks for small amounts are often paid by the bank itself because it's cheaper than actually disputing with the merchant, so banks will certainly terminate accounts of customers who abuse that.