My (admittedly loose) definition of BIFL is something that genuinely lasts as long as it possibly could within your lifetime, either through repair, ease of maintenance or within a reasonable time period of use.

Nothing is truly "BIFL", hell even rocks aren't BIFL since they wear down and break.

As others have said, computer mice can't expected to last decades of heavy use, in the same way that we don't expect shoes to last 80 years (but 20-30 years is pretty good). It's just not possible for the kind of product that it is - they will wear eventually. Reason why I posted this product is because I think it is one of the best built, most durable products of all the mice, certainly lasting much longer than anyone would expect a mice to.

That being said, I'm disappointed to hear the rubber coating wearing faster than expected - shame, because all the components inside have been reinforced for durability and longevity. I'm about 2 years into my MX Master 3 and haven't come across anything other that cosmetic wear on mine.

Should add: I own mechanical computer keyboards that I would consider BIFL, because they are made of far more durable materials and can be serviced by a competent user even if they switches wear out (which is unlikely). Keycaps can be easily replaced by anyone as they wear out. I just don't see the same emphasis on long-lasting quality in ANY pointing device you can buy today.