Biggest restriction is its adaptation. Majority of the countries, still, are not into cryptos as a digital currency, to be used in services and transactions. There are indeed advantages of it but countries wherein Bitcoin and other cryptos are not supported, are concerned with its price volatility. If it would be a medium of transactions, its value sbould be consistent in order to promote equality. Just think of it; if the price still is not stable, those businesses which would accept cryptos as payment will be at risk from doing so. They will be at risk of partially losing profit. Given that no one knows when will an uprise movement occur, the money would be "sleeping" instead of being a continuous amount to boost the business itself.