It's attention, not money, we should budget

The golden ratio for equipment $$$ allocation is as fallible as the golden ratio in room measurements.  IMHO.  I would agree with you that the biggest return on investment will be Speakers, Preamp, Amp and acoustic treatment.  

Interesting point. My budget has always been nearly non-existent, so bargains and DIY options (time) have been a requirement in assembling my system. In that regard I’d have to agree whole heartedly because time invested can pay off big.

If my income were much higher than it is now, I’d likely have taken a different path, but I’ll never know! ..... there are downsides there as well.

@erik_squires 100% agree spending time/attention and experimenting with an open mind can pay huge dividends.  It has for me. It seems to me many give up on a component/speaker prior to finding their true maximum performance and assuming a more expensive  purchase will be the solution. Often times leading to a  string of purchases feeding the used market.  In my case, I bought a used $9000 highly resarched/regarded amp to replace  a $3000 amp that had several easy tweaks.  The hugely disappointing new amp had inferior SQ and resold. However, other less expensive component changes have payed off after research.   Another example is when I restarted this hobby 3 years ago I bought a pair of speakers for $1400 shipped thinking I  could grow into them and then replace as they reach their max. They have shocked me with what they can do..I still own these speakers and I still hear SQ  improvement's out of them. (Tubes, fuses, cables, components, power…) In fact, I am hesitant to spend a lot more money to upgrade them and get inferior SQ and deal with the difficulty reselling large heavy speakers.  Granted this is just me, my ears and pretty modest system.

Using lots of time, attention, and money make for the best systems. We are all budget bound on one or more of these. So if financially bound, then invest more heavily in the others. What your time is worth is both a function of how much money you make per hour by working and the enthusiasm and available time you have to pursue high end audio. But time and attention are also limited commodities and dependent on your values.

As far as percentages… some folks have little ability to influence the room, many cannot. Often folks have a much larger ability to impact the financial investment they make.

As far as the price of components… yes, price in itself does not take into account your tastes, synergy with your system and venue, and may not perfectly represent sound quality. On the other hand it is the one common characteristic shared across all components and the meaning which is understood by all. Certainly, by itself it can only be a very rough guide. But for most, it is a good starting place. Also, most of us start with a budget. If you research, find best of class that matches your tastes beyond simple price you will be making pretty good decisions.

Then finally there is a question of how efficient is the market? What is the relationship between price and performance? This is particularly true once we get above budget gear. If you understand sound quality and are able to separate different house sounds, in general the sound quality rises with price. Much higher design times, higher quality parts all result in better sounding equipment… lower noise floors, more dynamics, higher reliability. This relationship is often obfuscated by the different house sounds… McIntosh produced extremely good sounding equipment… but I do not like their sound… so I could easily label them over priced. For me, same with Wilson. I don’t, because I know better and I can hear what they are trying to achieve. Also, ones individual venue and your other existing components highly influence the sound you get… not necessarily a reflection of the quality… or cost for that matter of the component you put in it.

Overall, however, I have followed dozens of high end audio companies over decades and compared between them. And with the caveats above… price of components is an important shared parameter across all audio that is very useful and largely reflects the sound quality of the component. Of course there are some exceptions… but they tend not to last long, because they are weeded out of the market by folks like us.

The problem with cost is X dollars buys you different things in different product lines. It may be true that more $$$s typically buys you more within a particular product line, though often with diminishing returns, but all bets are off comparing different product lines based primarily on cost. Especially if components in the system are mismatched as can easily happen between amp and speakers and room quite commonly. Source components require careful matching as well, for example phono components in particular. A well executed integrated design end to end always wins regardless of cost.