You need to make sure that it's bearings. Pull the bearings and inspect them. (This doesn't cost a penny to do.) You might want to check the preload before removing them. Proper bearing tension is: Tighten the castle nut with a few pounds of torque, and rotate the tire. This seats the bearings. Loosen the castle nut.

TIGHTEN THE CASTLE NUT FINGER TIGHT AND BACK OFF UNTIL THE FIRST SLOT YOU CAN INSERT THE COTTER PIN.

This is proper bearing tension and they'll last forever--mine have over 500,000 on them, and they are like brand new. If you tighten them beyond finger tight and backed off to the first slot you can insert the cotter pin in the castle nut, the bearings are too tight and will wear out prematurely.

I doubt very seriously, that the bearings are set too loose because many people cannot fathom the concept of correct bearing adjustment. As a result, the bearings may be shot.