“The difference between a collector and a hoarder is a display case.” -John Hodgman

Consequences. If it's disposable income, your hobby can be blending $100 bills into mulch to grow a bonsai tree. If you are eating up your retirement at 40, it's a disease.

Of course I'm not an expert whatsoever. Just my loose sense.

Around $5,000.

Lots of really good low-hanging-fruit actual improvements and solid equipment in that price range (combined, for the whole system); above that you're just getting crazy, and likely seeing marginal gains you can't actually hear and/or aren't worth the cost for what you (maybe, possibly, unlikely) might be fooled into hearing.

Another case of first world problems I suppose?