Despite a decade of use and a twelve-figure market cap, it's still not clear whether cryptocurrencies like bitcoin are here to stay or will cross over into mainstream use.

Some experts, like Nobel prize-winning economist Robert Shiller, are pessimistic. On CNBC's Trading Nation, he called cryptocurrencies a fad on par with the Dutch 'tulip mania' of the 17th century. On the other end of the spectrum, Myron Scholes, another Nobel laureate, is helping to develop a low-volatility cryptocurrency called Saga (SGA).

One factor many agree could make or break cryptocurrency is whether it can outgrow its current appeal to the FinTech crowd and join the real economy. It all depends on whether consumers adopt cryptocurrency as a payment method like any other. So far, they have proven reluctant to trade their fiat bills for crypto coins.

Here are four reasons why, and some solutions, too:

Crypto is hard to spend

Probably the biggest obstacle to the uptake of coins like Bitcoin and Ethereum into the real economy is the lack of opportunities to spend it. Even though more than half of Amazon customers would use an Amazon coin for their purchases, actually doing so remains basically science fiction.

Liquidity in crypto markets is shaky. Since it's hard to make real life crypto purchases in most big marketplaces, the coin holders aren't always able to fulfill their holdings.

"In order for cryptocurrencies to become mainstream, the infrastructure surrounding it must be user friendly and efficient," Guy Melamed of Zeex, a network to exchange gift cards with cryptocurrencies, tells me. "Otherwise, adoption may be limited to a select tech-savvy audience as it has largely been until now."