It is a matter of free time, ability and temperment. I see myself on one end of the spectrum. I have some mechanical ability. I have no time, and my temperment is, well, type-A...to say the least. Therefore, new suits me well, and in fact, I wouldn't have it any other way. Don't get me wrong, I don't have to have a new tractor every year, I'll drive mine until it is dead or is taking up so much time and money to keep it going that it is no longer worth it. I just like to start new.
On the other hand is my B-I-L. He hates new. He hates shiny paint.He doesn't like the look or style of anything modern. He hates new car smell and all the extra expense that goes along with anything new. He is a full time rancher. He has 8 or ten machines, all old, newest tractor is probably late 70's early 80's. His two big Case tractors look like late 60's to me. Of the 8 or ten machines, I'd say 5 of them get used almost daily. He has a full shop including a massive overhead hoist for cracking the tractors. We'll start some sort of project, moving hay, or whatever and one of the tractors will break down. He'll cuss and fuss for a few minutes but then as he starts the process of fixing the thing, you can tell he likes working on them. He'd just as soon be in the shop tearing the tractor apart as moving the hay. With my personality I would come unhinged. I'm sure I'd blow an aneursym if that happened to me all the time.
The irony is, its catching up with him. As his kids go off to school he can no longer send the oldest out on another machine to move hay while he is repairing the first one. Its also going to take a toll on him physically. He is toying with the idea of a big new 4wd with a cab.