In my own experience, (I've not always only been a "stamp guy"), when one sees the word "investment" attached to anything collectible, one has to be very very careful.
How I like to describe it to stamp collectors that are thinking of "investing":
One doesn't by shares of companies based on how pretty their stock certificates are or 100 of each new share issued, or only orange stock certificates. To properly invest in the stock market one has to investigate the companies, their industry, related performance and many other things before purchasing their stocks.
If one wants to invest in stamps, or lego, or coins, or any other collectible, the same research is required. This means much more time is spent investigating the relative value than simply collecting for fun.
While the general population is seeing it as an "investment" the value goes up inordinately, as in non-collectors are buying it as an investment. Generally anyone can make money by buying and holding and reselling in a relatively short time period (this is rarely manageable in the collectibles world because markups tend to be high). At some point the demand softens and the prices drop down to the "collectible" value as opposed to the "investment" value and because there are a lot fewer collectors than there were investors, prices can drop a lot.
This has happened with stamps, sports cards, pogs, comic books and likely lots of other stuff too in my selling career (38 years).
I think "collecting" and "investing" sometimes are incorrectly interchanged in peoples minds.....
Certainly in almost every category the "right stuff" over the course of time can be a good investment, but there is not a lot of "right stuff"....
