Driving a vehicle with Bad U Joints is never a good idea.
I've driven with bad U Joints myself and my driveshaft under my truck actually dropped out and then caused me to go off the road.
Your U Joints are very important to your vehicle and without the U Joints the vehicle will not move and when the U Joints to break your driveshaft will come out from under your vehicle and cause you to lose control of your vehicle.
I replace my U Joints myself as preventative Maintenance after about 150,000 miles which is a lot of driving for me.
If my U Joints have 80,000 or more miles on them and I plan to go on a road trip longer than 1,000 miles then I go ahead and replace them.
Or if I need to remove the driveshaft to replace a transmission seal then I replace them.
U Joints are pretty cheap and it's good to know I have good U Joints on my vehicle.