Comparison - car wheel and jet engine?
I knew someone would jump on the recklessness of my statement (quite rightly in a perfect, no-risk world) but what I mean is that if you have only just become aware of a slight bearing noise there is no need to panic and cause yourself great inconvenience for a few days until you can get it fixed - certainly just for short journeys. It will, eventually, get uncomfortably noisy so that you don't want to drive on it before it breaks down.
A jet turbine on the other hand is spinning at hundreds of thousands(?) of rpm under unimaginable loads and temperatures compared with a car wheel and can presumably degrade in minutes if not seconds, with cataclysmic consequences.