IMO, people just don't see the increase in performance to be worth the increase in price.
Now, something like the Sony MDR-7506 has an excellent performance-vs-price ratio, but many people want to stuff their headphones in their pocket when they aren't using them, and it is hard to find the same performance-vs-price ratio for earbuds.
Personally, I'm at roughly the same spot as you. I have a DAC and amp, and two pairs of nice Senns.
Now, something like the Sony MDR-7506 has an excellent performance-vs-price ratio, but many people want to stuff their headphones in their pocket when they aren't using them, and it is hard to find the same performance-vs-price ratio for earbuds.
Personally, I'm at roughly the same spot as you. I have a DAC and amp, and two pairs of nice Senns.