Where is the significant point of diminishing returns on hi-end turntable?

My apologies to all for the troll feeding. This is an interesting thread and I did not mean to cause any trouble.

So, do you think, with the wide range of views about where the point of diminishing returns kicks in, it is fair to say that the answer varies-- depending on a number of factors (system, record collection and budget, among them)?

I’ll throw out one provocative thought regarding the "money issue" which seems to be an undercurrent here-- that obscenely expensive tonearm that a few reviewers, starting with Fremer, have raved about--the SAT? (i think that’s the brand name). Crazy money, right?
But, what if, by using it, you can use far more modest cartridges? Top tier phono cartridges are nutty money today, and are "consumables"- so the cost of several cartridges would offset the extravagant price of the arm.
One last thought--for now. I have a fairly big league table and arm. It isn’t the latest and greatest and that is, in some ways, the point--I haven’t found a need to upgrade, modify or replace it since I bought it circa 2006-7. (Replaced a few belts and the manufacturer supplied one replacement part at no cost since I’ve owned it). In the long run, cheaper than trading up or sideways periodically.

I think the reason that the question posed by Dr. Porsche has elicited so many disparate responses (and arguments with nattering nabobs of negativism) is that the question calls for subjective opinions; we all have one.  I have always had the "feeling" that there is a point of diminishing returns when it comes to all or any type of audio gear, but I have no idea where that point lies.  I don't think any of us have an answer that is generalizable to everyone else.  This dilemma has made a cheapskate out of me, most of the time, and induced me to become a DIY tinkerer and builder.  I do know what capacitors and resistors I prefer, but I could not and would not dare tell anyone else where he or she should stop spending money on a turntable.  For me, the "answer" is either my SP10 Mk3 turntable, heavily tweaked in a custom 100-lb slate and cherrywood plinth, in which my net investment is around $8K or my Kenwood L07D, restored to OEM operating condition, at an investment of about $3800.  But others who prefer belt-drive turntables would scoff at those choices and those valuations, preferring instead some modern $50K piece.  I don't take issue with that.  This is a fun hobby. I've heard the Walker turntable in its earlier iterations, and it is indeed superb, best sounding belt-drive I ever heard, but I am happy with what I've got.
So, Porsche baby, perhaps you should re-phrase your question or else take the responses that appeal to you the most and go for it. (In my lifetime, I owned just about every model of 356 Porsche ever made, up to and including a Carrera GT Speedster, and then a 550RS Spyder.)

lewm- you had a real 550 Spyder? Did you own it a while ago, before these cars reached Van Gogh painting prices? One of my heroes is Ed Niles (not even sure if he is still around). He bought, imported, drove and then sold (to fund further acquisition of) some of the great sports cars of the '50s and '60s --bought them when they were just tired old oddball cars on a professional's income (Ed was a lawyer). 
It is a fun hobby. Nice post.