Users make money via asset appreciation over time.
How They Make Money
They make money through the transaction fees they offer. See further details at https://help.coinbase.com/en/coinbase/trading-and-funding/pricing-and-fees/fees
What are the Investment Risks
Cryptocurrencies possess high amounts of risk due to their volatility in the market. The risk can be loss of principle as there is no assurance that there will be positive performance over time.