Are audiophile products designed to initially impress then fatigue to make you upgrade?

 No, not if you bought the right components in the first place. By right, I mean don't buy overly analytical or bright equipment.

Why those little sneaks….😠

Planned obsolescence does exist in mass produced gear like Denon/Pioneer/Yamaha AVR gear.

I disagree with the premise that better quality manufacturers design goals are to lure you in, then some magic switch goes off to produce sound that is intentionally  fatiguing.

But it's a great idea that I'm sure the low-end sales guys would love.

Yup, it's a bloody conspiracy, for sure. It's amazing that you figured it out. Congrats!

What do you plan to do next?

Yes, all of that is true. Stop spending money on hi-fi equipment and go home.