I'm not sure I understand the question. We are talking about a TRex 550 that is still a current model (not discontinued by the manufacturer), and all the broken parts have been replaced after every crash?
Unless the crash makes the helicopter un-economical to repair, it is worth keeping. Now crashing is a part of this hobby, specially when learning. You will crash less as you gain experience. From my experience, keep up with eye exams. I thought I was good until I dumped about 3 helicopters in a span of about 2 months. When I got my eyes checked, the doctor told me that my eyesight had deteriorated abit since the last checkup and I had gotten used to it.
I have a Raptor 50 that dates back to the V2 days (circa 2004) that I still fly regularly. I own a couple of Hirobo helis older than that (I got them used) that I also fly regularly. If I can find parts to repair the helicopter, it will not "retire" it. When parts become hard to find, then I recycle components and retire the airframe.
Rafael