Collectible investment character

Some rich people or great man collects unusual goods as their fan. They dare to spending million dollars for the collectibles and they also dare to go everywhere for hunting collectibles. There is a satisfaction to see the collectibles in leisure times. They also are pride to show the collectibles to other rich man and colleagues. The Rich people collect some collectibles and antique things such as art, coin, painting, stamp, baseball card, basketball card, ring, and others. These things can be an investment like other assets. However, you should know the character of collectibles. Those collectibles character like this:  No one know the value exactly Collectibles is different with the gold price. People know that a troy oz gold is around $ 1,500 but they do not know the price of collectibles gold coin. The gold collectibles usually more expensive than the common gold coin. The old gold coin has historical value.  For example, I will not pay a babe Ruth basketball card even for $ 1,000. I am not a basketball collector and I do not know what baseball is. To me, buying a basketball card is not profitable investment.   Not Liquid  The collector cannot sell the collectible anytime like selling stock or ETF. The collector should find the right buyer to get the right price. Only crazy collectors who want pay your collectibles over many times. Alternatively, you can sell through bid house. You have to pay to the house first. Perhaps the rich people will buy at the bid house. On the bid house, the rich may buy the collectibles high but sometimes they buy cheaply.   Alternatively, you can sell the collectibles on online such as Amazon or eBay. I saw there are so many collectibles on eBay such a coin, stamp, art, and others.  This is the weakness of collectible investment. That is why rich man should not put all money to collectibles.   Few demand and market  Only rich man or antique shop that want to buy the collectibles. There is few collectibles market.    Long time investment  Collections is a long time investment that can generate revenue for long time. If you save for long time, it prices could be multiply over many times. This investment is not suitable with common people who want short term return.   There are so many fake collectibles
A bad people often imitate the collectibles to get much money. The imitation process is sophisticated so the collector often are fraud. 
Fragile  The collectibles often fragile due it is old. The collector should maintenance the collectibles. For example, you should polish the coin.