The "impulsive" situation you mentioned exists, but the number is very small. The funds are all billions of plates, and only a small proportion of customers are "impulsive", which is completely lower than the level of the opening plunge.

First, the net value of the fund depends on the rise and fall of the stock, and has no influence on the subscription and redemption of the secondary market.

Second, ETF and LOF may have a price difference between the secondary market and the primary market, but this price difference will be corrected immediately by arbitrageurs.

Third, there are some new open-end funds, with the price difference between the primary and secondary markets, but generally at a premium.