Can an “audiophile” ever be satisfied with a system?

I don’t think “satisfied” and wondering if you can do better are mutually exclusive. To me “satisfied” has connotations of a value proposition. If you get the same sound with $50k that you did from $5k then that would be problematic. The sound you are getting can still be fabulous, but it’s hard to remove expectations based on price. The question isn’t so much can I make it better (always), but what’s the best way and how much will it cost?

I think it is when you are most satisfied with your system, at any given moment, is when you want to make it even better. 

If you weren’t satisfied, you may have given up trying.

Yes... since I got Don Sachs' tube front end, the Aqua La Voce DAC, and Spatial Audio speakers in my system.  I am extremely content with my the sound of my system.  

OP, Interesting question which really is very psychologically particular to you. Not knowing you, here are a few takes:

One is that you have to stay on the Merry Go Round because you seek Nirvana and since you’ve never been to Nirvana, you can’t know what it sounds like. You’re on an asymptote. It won’t end.

Another is that as you’ve grown, you’ve learned and because you’ve learned, you’ve realized how much more there is to know and experience. Something Millercarbon said in this regard made me think that we’re not "trapped" in some kind of circle but are rather on an evolving spiral. The question he raises (I think) is, "Are you learning to listen?" Because if you’re not doing that, then you’re really just a shopaholic and that is a non-evolving circle.

Some with this hobby just seek out "flags" to wave. Once they find a brand of speaker, amp, etc. they just decide it’s "the best" and then it becomes the magic word answer to about half the questions. In other words, for some, the question of "Am I there yet?" is answered by a brand.

Then there is Steve Guttenberg’s answer -- which I really like. He says that the quest for the "best system" is a mistake. It’s better to seek a "good enough" system ("good enough" to sink you into the music) and then if you’re feeling antsy, to realize that boredom may not be dissatisfaction with one’s system, but a desire for a different sound. Some nights we eat Italian, other nights Chinese food, etc. In other words, hearing music with different gear (or tweaks, cables, etc.) adds "variety" and not "betterness." Variety is the spice of life.