Why Are Proofs Generally Less Valued In Resale Markets?

Look at the populations reports. More proofs are ordered from the Mint than business strikes. ==> Less business strikes available in the secondary market.

I think there are a number of dealers who will buy large numbers of sets from the mint, look to cherry pick the best coins hoping for high TPG grades and then dump the remaining sets for what they can get for them.

. Every dealer in the US has one (if not many more) boxes of proof sets that they can't sell. The market is so saturated that dealers will sell them below bid just to get rid of them.

I think the last sentence in my post demonstrates that I get the "Econ 101" concept that there is less demand for them; I guess I'm trying to get at the root of WHY. Why are they less popular when they're objectively "prettier"? --I do mean good proofs with good strikes, not something like the 1960's ones that look like spray-painted plastic, but you know, well-struck ones with deep white cameos on black mirror fields.
Matthewvincent--I'm not sure I understand your comment about the numbers of orders from the mints. You don't have to buy a mint set to find upper-60's grade business strike coins of a given year; there's at least one in every few new rolls available at your local bank.

I definitely get what you're saying, but consider the math this way: Look at the 2018 Roosevelt dime, just for a random, recent example. There were only 500k proofs minted, while Denver and Philadelphia minted a total of over 2 BILLION. Even if only one out of every thousand was selected for its' flawlessness by a collector and put into a flip, that would be 2 million, four times as many potentially high-grade business strikes as proofs.
But now that I'm looking at these numbers, it seems that they used to make a lot more proofs (1-3 million in recent-moderns of all denominations) and they just started putting the brakes on in the past few years. Now THAT is interesting, like maybe they're trying to increase their collecting value by lowering supply? Or am I misundersanding how it works, like they continue minting them after the year is passed?

There is certainly no difficulty finding a PRF 69-they are pretty much all at least that (if they were not, the mint is not doing their job).

As I understand ms-66 and higher are much harder to find. Even though there are 2 billion issued for circulation, how many are MS 69?

This is not how it works. Proof sets are minted to demand, so the lower mintages are because people are buying less sets. Newer proof sets have more coins in them (Native American Dollar, ATB Quarters, Presidential dollars, etc.) than the older sets do, thus the issue price is higher.

Here is an older collectors idea on all of this.
When I was a kid, communications were not as instantaneous as today. Getting a new coin for the album meant either making a trip to the local coin shop (if you had one - urban areas only), finding one in change, or waiting a whole month for the next issue of your favorite coin magazine so you could check the lists and mail order them. We won't mention Littleton.

The hobby was mainly all about the anticipation of hunting for and thrill of finding (you hoped) hole fillers from change/circulation. Regular issue coins is what it was all about. And since there was no eBay-instantaneous-buy-it-now full collection of (let's say) Franklin half dollars at your cell-phone-dancing-fingertips 24/7, the hunt to complete your album/set was what it was all about for most people.

Plus the makers of those "little holes" rarely ever included (if at all) holes for proof issues. Why were no proof issues included in the albums? Again, the mindset seemed more to be that a "complete set" was made of "regular coins" anyone had a chance of finding in circulation. Since proofs were just the mint showing how perfect they could make a coin, proofs were not normal coins and certainly were just extras not to be confused with being a part of the "actual" (album-hole-defined) set.

Had Whitman made holes for proofs, things may have been different. But, then again, maybe not. Some other company may have become dominant that "knew" it was taboo to break coins out of a proof set (more on this later).

Think of typical car - normal coins. Think of curb feelers on a car (dating myself) - proof coins - not standard issue.

Just like an awful lot of collectors are afraid to crack a coin out of a slab, back in those days no one would be crazy enough to break apart an officially packaged, "US Government Mint Proof Set." After all, the marketers made sure we were aware proofs were incredibly special coins being of the highest possible quality, and (a big point here) no human hand had ever touched them! A handled proof coin violated this no-touchy rule and stripped the coin of its sacred status/value. Proofs were a world apart from what went into our "complete" album sets.

Another point is proofs lacked the fundamental thing which keeps hobbies alive: the thrill of the hunt to bag something special. Anyone could have a proof by throwing money at them, however not everyone had found a 1932-S quarter...yet!

I think the old stigma of proof coins only being a sideline special issue kept the prices low when the internet appeared. As the newer generation has come along, they see tons of proofs online for very little money. Hence the lower mintage eye candy coins are seen as having no real value to them.

Albums with proof holes are more well known now, but the vast majority still don't have those holes. So except for a few special sets for eye candy, few people still want the proofs.

Admittedly the idea that a complete set is one from regular issue coins (with a few exceptions) is so deeply ingrained in me that I don't go after proofs. I make an exception on Ikes and Kennedy halves simply b/c, for some reason, I just want them.