Ball Joints typically last at least 70,000 miles before they need replaced.
The lifespan of the ball joints depends on your driving conditions as well and if you drive on rough roads more often then the ball joints will wear out faster.
If you drive mostly on smooth roads then the ball joints will last longer.
In my experience ball joints for me last between 70,000 miles to 100,000 miles.
My dad's truck has the original ball joints and his truck has 300,000 miles and they seem tight.
However he's gonna replace them soon when doing other front end work just as preventative maintenance.
If your ball joints have 100,000 miles or more on them then it would be a good idea to replace the ball joints by then as well.