With completely wireless earbuds, the rule is: when the battery fails, they have to be disposed of. Not so with the Fairbuds, that allow you to replace batteries in just a few seconds. Combined with a repairable design, the earbuds should therefore have an extremely long lifetime.
Every 2-3 years in my experience, I’m on my 5th or 6th wireless headset in the last decade, and most of those were replaced because the battery life went to shit. And I’ve tried multiple brands with no material differences in overall life, but I also use mine throughout the day every day and regularly wear them until I’m forced to charge them.