How does Coinbase earn work?

Could you elaborate on how Coinbase's earning mechanism functions? I'm curious to understand the various revenue streams that contribute to its profitability. Does it primarily rely on transaction fees? Or does it also generate income through other avenues such as interest from lending or staking services? Additionally, how does Coinbase ensure that its earnings are sustainable and scalable as the cryptocurrency market continues to evolve? Understanding these aspects would help me gain a deeper insight into Coinbase's business model and financial performance.