When does the law diminishing returns kick in?

As I go through these threads reading responses I will look at the systems from answer writers. Wow, some of you guys don't mess around. As a music lover and audio guy myself (since the late 60s) I can't help but be envious.
Although my system is modest, especially compared to some, I get a lot of enjoyment listening to music on it. It took a while and a lot of trial and error to get what seems right to me. But when looking at the super systems here it makes me wonder what I'm missing. With the exception of deeper bass, am I missing all that much? How much would I have to spend to hear real (worthwhile) improvement?
p.s. I think FatParrot is onto something with his geometric quantum progression. New laws of economics being discovered here.

Jond's bold identification of $2K as the specific point of diminishing returns, give or take, also accords with my experience across a range of components and manufacturers. Beyond that, its not that you can't hear any difference, but you can pay a lot for modest gains, and wonder whether you are really enjoying music that much more.

There those who needn't balk at $10K or $20K, or $100K per component but they probably wouldn't look at this thread.
It's probably the old hippie/commie in me that balks at spending $10K or $20K for a piece of audio gear. But I admit the world would be a less interesting place to live if everyone were satisfied as simply as me. And what would Hi-Fi reviewers write about?
It kicks in when you stretch really far to buy a component that's 3X or 4X more costly than one you have, discover is sounds about 5% better, and are told by audiophile friends that if you only spend $X,000 more on addtional [fill in blank], "it will make your jaw drop."
When you KNOW where the next SIGNIFICANT sonic improvement lies and you can't comfortably afford it. Diminishing returns is a relative concept; one of its parametres is personal means.
Remember, however, it's good to LIKE what you have (rather than to strive for what you "want" and can't afford). And $10k is a LOT of money for anyone -- no doubt about that. Cheers