Earlier this month, foreign media reported that the gold sales business of major US retailer Costco (Costco) is booming, and it is estimated that the revenue may reach 100 million to 200 million US dollars per month. At the time, whenever Costco launched a batch of gold bars, these bars usually sold out “within a few hours” because shoppers would rush to buy them at slightly higher prices than the spot price.

But now, according to the Wall Street Journal, when it comes time to cash out, many people will be aware of the harsh truth: gold isn't the most liquid asset. It's much harder to sell these bars than if you can buy Costco bars by adding them to your shopping cart.

Costco will not repurchase gold bars and will not accept returns. So the only way for buyers to cash out is to find other people willing to buy gold bars from you, which is more complicated than some might think. They can only change hands through online and offline resellers who will charge extra fees or only buy at a lower price than the market price.

Online retailers, refineries, and local stores in New York City told the Wall Street Journal that they usually buy back 1 oz of gold bars at 1 to 5 percent less than the market price (that is, the spot price), and not at the market price or above the market price.

Investing in gold is often a “buy-and-hold” (buy-and-hold) strategy to preserve value during periods of economic fluctuations, such as inflation. However, precious metals traders said that after the price of gold rose by more than 15% this year, more and more people are starting to sell gold bars and jewelry.

Robert Pacelli (Robert Pacelli), CEO of online buying platform JM Bullion, said that in March, the platform's customers sold twice the monthly average in gold.

According to the data, there are more than 1,700 gold and silver traders in the US. That doesn't include jewelers, refineries, and other non-specialty stores that buy gold. Traders will quote based on current spot prices, which fluctuate throughout the day based on supply, demand, and futures contracts.

As more and more gold holders try to profit from the rise in gold prices, some traders say they are reluctant to offer competitive offers. When asked about gold bars, a representative of the Money Metals Exchange said they had too much inventory, so they had lowered their offer.

Selling gold online also comes at an additional cost. According to JM Bullion, shipping costs can be as high as $40 per ounce of gold. Gold bars worth $2,000 require an additional $40 in shipping, according to US Postal Service data.

Profits from holding gold for more than a year may also be subject to higher tax rates than other long-term investments. The IRS generally treats gold as a collectible item. This means that the capital gains tax rate could be as high as 28%. According to the IRS, the maximum tax rate for stock investments is 20%, not including the 3.8% surtax on investment income.

Tom Graff (Tom Graff), chief investment officer at wealth consulting firm Facet, said investors can expect the value of their gold holdings to depreciate by about 5% immediately, due to premiums paid by buyers and the costs required to resell.

Gold investors are relying on price increases to recoup these costs. Although gold prices have been rising recently, historically they haven't continued to rise like stocks.

Facet's Graff said, “You need to hold on long enough to offset this cost.”

Luke Greib (Luke Greib) of southeastern Michigan waited nearly a decade to profit from his gold bullion holdings. In April of this year, he sold his 1-ounce Credit Suisse gold bar for $2,350, and he paid $1,500 when he bought it in 2015.