I have friends who never buy new computers, instead they get frankenputers assembled from mismatched old parts put together for free (or rather, at the cost of a couple of beers). These computers work just fine unless you're playing newest games with high settings, which is completely fine by them, since if they were gaming enthusiasts, they would buy new computers anyway.
Getting rid of old parts has a low profit margin and people generally have no energy to do it. If your friend can get a workable rig from them, most computer enthusiasts are happy to help. The practice wasn't really possible in the 90's when old parts became obsolete at an alarming phase. This hasn't been the case for some 10 years.