Certainly. A HDD contains a bazillion of very very small "magnets" only a few atoms in size. The disk might still work fine due to redundancy and/or error correcting codes even if
a good amount of those little magnets lose their magnetism or flip but sooner or later too much of them will fail and render the disk useless.

Your fridge magnet will probably still work fine with a few magnetism left.

You should check your the website of your HDD vendor. They tell you detailed specs of any model. My drive, for example, is "designed for 5 years". Incidently, as a rule of thumb, I wouldn't trust any media more than 5 years.