For all intents and purposes, cryptocurrencies are purely speculative because they have no fundamentals to drive demand or influence prices. It's worth contrasting this situation with other investments, which do have fundamentals:
Bonds pay periodic interest and repay their principal on maturity. The expectation of these future payments sets demand for the bonds. Prices can be influenced by changes in interest rates or changes in the creditworthiness of the borrower.
Stocks represent ownership stakes in companies that (hopefully) make profits that will eventually be either paid out as dividends or reinvested to make the company more valuable. Expectations about these earnings drive demand, and prices can be influenced by changes in earnings projections.
Commodity futures represents contracts to buy or deliver commodities such as oil or agricultural products. These commodities are used by firms to produce products and services (e.g., airlines buy large quantities of jet fuel, an oil product). Prices can be influenced by these companies forecasts of demand for their products (e.g., forecasts of passenger volumes) or by commodity producers' forecasts of their ability to meet demand.
National currencies are used to buy things in their respective countries, notably including exported goods and services. Thus, their prices can be influenced by global trade balances.
Of course, all of these markets have their share of speculative demand, and often speculators provide an important source of liquidity in the market. However, in all of these cases there are fundamentals that set the basic parameters for the market.
Cryptocurrencies have no comparable fundamentals. In theory, it's possible that use of cryptocurrencies as currency could expand to the point where it provides a fundamental source of demand, similar to that for national currencies in foreign exchange markets, but for the time being that usage is negligible. Thus, in practical terms the demand for cryptocurrency is entirely speculative.