I do enjoy seeking the next better thing, because I do believe there is likely something more fitting to my tastes than what I already have.
I do tend to see the ability to scale down my ownership to one or just a few comes about from finding products that offer me either the most comprehensive package. To get to one, I think one needs to be able to accept and settle on the one best fit despite not being perfect everywhere. For myself, I've found this to be Ortofon's e-Q7. To my ears it offers enough of the right parts to be very good and work across a broad spectrum of genres. It offers balance, dynamics, texturing, moderate detail, and all the things I seek. I certainly don't see it as king though. I can look at other earphones that offer more in any one area. It isn't the king of everything. However, it is a jack of all trades which is something that can allow one to become content with as a solo device. It's something that does everything well and works well with everything. I think that is the key to being able to step down to just one.
Yet, we always enjoy speciality, products that offer us unique sounds, exceptional capabilities in certain areas, and we always still seek that next better thing. In this sense, I think we are bound to an ever changing array of personal hardware as we cycle through what's out there. We certain end up with some particular favorites that at the very least show us some aspects of best or ideal even if the total package isn't perfect. There are also a slew of holistically very good earphones out there, each just tailored slightly different from each other to suit varying personal needs. There are certainly many earphones I view as on par with each other, just different, as well as many earphones that are very near my preference that fight in very tough competition. I tend to keep such close performers unless I can unequivocally pick one over the other. That's very tough to do unless I can say X is better than Y, and that's hard to do with a lot of these. You end up with a lot of very good products on equal ground and with gearing quite similar to each other or at least geared very near your preferences.