Of course there will be more aging of certain parts used at higher temperatures and longer periods but I've yet to hear of a "worn out" Bryston amplifier. My close friend, a gifted audio engineer who is not connected with the company, has told me that Bryston is truly as fanatical about selecting the best components available as they say they are. By over speccing heat sensitive parts, they are much more durable, as you would expect if they are going to treat it as their own for 20 years.
I routinely would drive to their factory (until now, obviously) with old equipment belonging to friends and customers for recapping and these would be restored to at least new performance for a very modest price because they don't see repairs as an appropriate profit source. When I've bought used 2Bs, 1Bs and .5Bs, I never even turned them on because nothing is like new after three decades but the repairs when needed were always trivial.
Lastly, in my experience, it is highly unusual for anything to be used very hard in the real world, although I'd say cars are abused routinely in various ways. Of course someone could buy a 2B LP for use where high sound levels for many hours per day are required but they probably won't.