I think there's two pieces of this that really deserve separate answers:
How can you set things up so that if you get hit with legitimate huge charges, you can handle it without all the money in your checking account disappearing?
Put everything on a credit card. This is US-specific since I don't know the details in other countries, but if you pay off your balance every month, this generally won't cost you anything. In some cases, companies will charge you a higher amount to pay with a credit card (since it costs them more). You can mitigate this in part by using a card that gives you cash back or points. Beyond that, I would just treat this as the cost of insurance.
The benefits of this are:
- You can pay the charge off over time (although you'll also have interest payments)
- If you declare bankruptcy, you might not have to pay the entire thing
- If the charge is actually fraudulent, it's trivial to reverse it
If you have the option, you can also turn off auto-pay. This will leave you the ability to put the charge on a credit card later, but you may also be able to negotate lower payment with the original company. For example, auto-pay for hospital bills would be a terrible idea because you can use the risk of bankruptcy as leverage to make the hospital either reduce your bill, or let you pay it over time without interest.
How do you avoid getting hit with legitimate huge charges?
I think the answer is:
- Choose fixed-cost contracts over variable-cost where possible (unlimited or subscription plans)
- If you make a variable-cost contract, ensure there's a limit to how high it can go (high deductable health insurance, anything with a maximum price)
- If you can't get a limit on the contract itself, try to limit risk some other way (buy third-party insurance, like with health insurance)
In the case of Griddy, the trigger to wonder if you're exposing yourself to more risk than you wanted it that they're passing on variable "wholesale rates". Similar things that should trigger your risk instinct are variable rate loans and overage fees.
I'm not sure if there's a general purpose way to avoid this, besides inspecting every contract you pay, but you could try to find general-purpose insurance. There's a thing called "umbrella insurance" which protects you from liability risk in general (assuming you're found liable for something but you didn't do it on purpose). There may be other financial products that insure against even more general risks. It's worth noting that the value of these depends on how much money you actually have though, since bankruptcy law caps your risk(at worst) at all of your money*, so it's umbrella insurance isn't worth it if you don't have very much money.