You might want to turn your anger dial down from 11 and stop using caps lock. Shouting at me won't make me change my mind.
Actually I have loads of Blu Rays and they look and sound far better than DVD (except DTS on DVD sounds pretty damned good when you can get it). The only reason I don't have 4K is no-one will sell me a 4K TV that fits in my room, 32" is the largest that will fit. That and I missed out on buying an Oppo 205.
Upgraded power supplies, sure the noise PSUs generate can get into the signal. I've worked with a former TAG MacLaren digital engineer who assured me that in blind listening tests people can identify one changed capacitor in a power supply.
As for interconnects, there's a difference between cheap rubbish and properly made ones. But above that I have difficulty hearing a difference, I have owned a couple of pairs and sold them on having found them to be a waste of my money.
Next you'll be telling me it matters that I connect the arrows on so called mono directional interconnects the indicated way round, despite the fact that sound is an AC signal so can't possibly be affected that way.
And I'm not a minimalist. I have a DC blocker on the mains into my AV amp, because it stops the transformer growling from time to time from DC offsets on the mains. I still have my S-VHS VCR hooked up in the system, if I were a minimalist that would have been removed years ago.