It worked out well for him but I think the scheme to buy dollar coins from the treasury and then use the same coins to pay back off the credit cards was brilliant. You also didnt have to involve employees in the schemes. I'm not sure what Avis will say to the branches he rented from.
Or they just spend five minutes thinking about attack scenarios. For example in this case, if they had added "one offer claim per customer per day" it wouldn't likely have impacted any of their normal customers (or sub-1% of them), but would have stopped stuff like this.
The dollar coin thing was always going to bite them in the butt. They were literally selling money at a loss (it was a dollar coin, effectively sold at a dollar not including postage). There are numerous ways to exploit that, it was moronic.
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Why do these people exist? I think that this in a way is a protest in response to the airlines and the way that they do business. Realistically, individuals have little power in exercising their disapproval of treatment by the airlines or from the effects of business decisions. (I.e. Award devaluations, stripping out connections to hubs at airports, monopolies over airports (I.e. CLT pre Southwest) Even as a group.. an airline won't respond to a person not flying with them.
He seemed to have fun, and the staff at the rental car company enjoyed interacting with him.
And I don't think this man did his mileage run to "protest" anything. He's probably a big fan of air travel, airports, and car rental companies and enjoys traveling.