I suggest the exchange develop/add a feature: When your user buys a altcoin, the system automatically marks the exchange rate price of the altcoin/BTC at that time. When the exchange rate of the altcoin/BTC drops below 50% of the buying rate, it automatically sells the altcoin for Bitcoin. The exchange only needs to develop this feature, and I guarantee that your leeks will continue to flow and you will always be grateful. Hope all fans can see it, one click triple connection! This is the life-saving function!