Why did SEC sue Ripple?

Could you please elaborate on the reasons why the Securities and Exchange Commission (SEC) decided to sue Ripple? As a professional practitioner in the field of cryptocurrency and finance, you would presumably have a deep understanding of the intricacies involved. The announcement of this lawsuit has caused widespread speculation and concern within the crypto community. Many are wondering if this is a sign of increasing regulation or if it's a one-off case. What are your thoughts on this matter? And do you believe that other cryptocurrencies or blockchain-based companies could face similar legal challenges in the future?