Q: maybe a wheel bearing worn out, how dangerous is it?

Thanks for your question. If it’s a wheel bearing, the noise generally doesn’t go away with speed although it might appear that way because the noise gets masked by other noises such as road noise, wind and exhaust. It is possible that it is tire noise (common), particularly if the wear pattern on the tire(s) is odd, or you have high and low spots on the tire or internal belt separation issues.

To check that, have the tire inspected - but you could also try moving the suspect tire to a different corner of the car and see if the noise changes. There are techniques a Mechanic can use in driving the car to "load" and "unload" each side of the car (by swerving) to see if the noise goes away. If so, then yes, it is likely to be a wheel bearing.

YourMechanic can evaluate that for you. Also, Chassis Ears wireless can be applied to pinpoint the area of the noise. Chassis ears are excellent for diagnosing wheel bearing problems as you can sit in your vehicle with a receiver, while on the road, and switch back and forth between various channels (individual receivers) that are physically attached to the parts of your suspension that could be making the noise. YourMechanic can also assist you with such diagnostics.

The hazard posed by failing wheel bearings varies quite a bit. To my knowledge, it is not incredibly common for a wheel assembly to completely off a car due to a "failed" wheel bearing. What typically happens is the bearing races get so pockmarked, the bearing becomes just incredibly noisy and it gets replaced so few tests are done in the field by car owners trying to see, "what happens if I keep driving it..." But, your general supposition is right on the mark: if it is a failed wheel bearing and if you drive it "long enough" it will self destruct and pretty catastrophically, too, possibly causing damage to other car parts.