No it's not safe to drive with cupped tires because when you drive on cupped tires you can get less traction because the high spots in the tires lose contact with the road.
Also there will usually be vibration of the vehicle with cupped tires which can damage the vehicle and may also cause you to lose control of the vehicle.
If you drive on cupped tires you're taking a risk and if the cupped tires are on the front you should rotate the cupped tires to the back and then put the better back tires on the front of the vehicle.
If you have cupped tires then something is wrong with the front end of the vehicle and you have a bad wheel bearing or even a misalignment so get the vehicles front end checked out if you're getting cupped tires.
If you put the cupped tires on the back then it becomes more safe and the tires should wear out evenly that way as well.