Why Do Graded Coin Values Mostly Seem To Decrease In Value Over Time?

There is a CAC certificate lookup for stickered coins https://www.caccoin.com/lookup/

Why can't I use the CAC Verification Search to look up a PCGS or NGC graded coin that has no CAC sticker to find out if it has already been reviewed by CAC?

Many coins that CAC has reviewed, but did not sticker, have been accurately graded by PCGS or NGC. However, CAC stickers only coins that are solid for the grade, often referred to as B quality coins, and those that are considered high-end for the grade, which are often called A quality coins. Those that are accurately graded by PCGS or NGC, but are considered low-end for the grade and often referred to as C quality coins, are not stickered by CAC.

Furthermore, CAC wishes to protect the interest of an owner of a coin that has been reviewed by CAC but did not receive a sticker. Therefore, CAC does not want to compromise the value of such a coin by disclosing a negative review by CAC.

There have been many fine points explaining why the price of top graded slabbed coins decrease but here are a few more I can offer:

A) The standard for proof coins is much higher than 40 years ago. This is due partly to the very success of the grading system instituted and institutionalized by the grading companies. Therefore it is far easier to get PF 69 from many countries issued today rather than 100 years ago.

B) High grade uncirculated common circulating coinage goes for higher prices than many proofs because these coins are used and most don't fuss over looking for top grades in circulation or mint sets because the return remains low for the effort it takes to find high quality gems. And it is usually NOT worth the cost of grading such coins for the risk of not getting a high grade for it. It is usually a few years after new issues that people even consider grading a coin and these are usually from mint sets. The supply of average of mid-grade uncirculated coins usually outstrips the demand in the short to medium term. However, it seems after about a 40 - 50 year lag new collectors who view such coinage as approaching "classic" status will slowly increase demand. Examples of this happening are common circulating coins from the 60's and 70's as well as one or two denominations from the 80's and 90's (for the former, Jefferson nickels in nice unc grade or lightly circulated with full steps, Lincoln cents and Roosevelt dimes from some years and for the latter, Kennedy halves and Washington quarters from the 1990's not banged up or Lincoln cents from after 1983 that have not developed ugly toning or zinc rot).

C) TH novelty of the slab itself has worn off a little except for the earliest slabs which seem to show some collectibility. Maybe thee NCG slabs showing their new grading scale will attract colelctors just for that feature but it will likely be just for the first year or two,

D) As has been written, one should wait as the coin market is awash with people flipping coins for a fast profit. It is always best to wait before buying and even selling to catch the initial rise in price before the fall can be tricky. Best to treat coin collecting as a marathon rather than a sprint.

E) A final point, for US coins the risk of devaluation of slabbed coins after the first year is especially high as the market is fairly mature and as a predominant economic power, the tendency is for the coinage to be valued more than those countries no economically strong. There are then bargains to be found in world coinage (and not just ultra-modern as far back as the 19th century) -- coins from Iran, India, Jamaica, Venezuela, and several other countries all offer low or modest mintages and some beautiful designs. One example is a 1930 Venezualan 10 Bolivares gold coin I purchased recently. Melt value is around $1809, mintage 500,000 and for a beautiful BU Unc I paid $350 in total. A comparable coin with higher melt value ($232 1/12/2023) is the Indian Head $2.5 US coin. If we look at the 1929 issue with a mintage of 532,000 the retail of one in a similar grade (MS64+) runs at auctions over the past 3 years according to PCGS around $1,000. This example underscores the risk of slabbed US coins to fall in value due to the maturity of the market as well as access to information about other world coinage that collectors are beginning to access and share these days.