Unfortunately, it is true that most investors only buy an exposure that represents the rise and fall of prices, and the saddest thing is not buying "air", but the depth and liquidity between air and stocks may be vastly different. Luckily, I encountered a platform with good liquidity and depth, earning 1 million on paper and being able to come out with nearly 1 million. If you're unlucky and encounter a platform with poor liquidity and depth, even if you make a profit of 1 million yuan on the books, you may cut your profits and leave because you can't sell that much money at all. So even with air, it is advisable to choose a larger platform as much as possible, as the fluidity and depth may be better.