As an aside, there are several credit cards that offer PRIMARY CDW (Collision Damage Waiver) - this means that if you damage the rental car, the credit card you paid with will cover all damage costs (certain exclusions like luxury cars). You don't even have to file with your own insurance. If you have one of these, it would be worth paying with.
Some examples off the top of my head are:
- Chase Sapphire Reserve & Sapphire Preferred
- US Bank Altitude Reserve
- United Explorer Card
- Capital One Venture X
- Any American Express card that's enrolled in American Express' Premium Car Rental Protection program (note the program is NOT automatic)
There are a truckload of other credit cards that offer "secondary" CDW - this means that you still have to file with your own insurance, they just pick up the co-pay. Obviously this is less good (but better than nothing) because then you still have an insurance claim on your record.
In either case, you still need to have liability coverage incase you damage someone else's car or person. That is LIKELY covered by your own car insurance in the US, assuming you have auto insurance.