Exchange is a platform to buy or sell crypto. There are many exchange already in the market. But which will be successful no one knows. You should be careful to invest in exchange, trade sites. I don't think we need more exchange. Many are failed project. Many have strict rules and regulations. They charge high fees for withdraw. Many exchange don't support promising cryptocurrencies pairs. Many are working hard to bring mobile app based exchange where people will purchase products and services with exchangeable local currency in a few seconds.
You are right about exchanges, new exchanges are not worth it to trade, olds ones like binance and coknbase are the best. But, that aside, it is also should be known that exchanges are vulnerable to hack than wallets, so, the amount that should be there shiuld not exceed certain little amount.
