Good professional speculators buy early after finding a catalyst (TSLA is going to be added to SPX? Buy!) Good professional investors buy based upon fundamental conviction (complete long hours of analysis and determine TSLA is worth a lot, buy!) Bad traders/investors sit around and criticize each other, and jump in at the last moment before the crash "Market makers" don't trade the way most people here think they do. MMs are either HFTs and are simply filling orders at volume to take the spread (which is tiny and you cannot compete with unless you are co-locating), OR market makers are block traders taking the other side of an order for their clients, which is typically at a discount to last price, and are hedging in derivatives or working their book along the path of volume through the day.
What will happen if the SEC prohibits Chinese stocks from trading in the states? Will there be window when people can sell their stock before delisting? Or, will you b required to hold the stocks indefinitely until they can resold later, and hope the stock has not lost any value?
Beware mixing Tsla with the Chinese EV makers and valuing them the same way. The Chinese EVs are proper car companies starting out in a huge market in which the government plays creator. Trading them is highly speculative because they havent sold cars outside China. Some haven't even built cars yet. Tesla is an energy company, making their own batteries for their cars, their retail focused PowerPacks and their industrial energy storage. They also have a million cars on the roads and factories on 3 continents.
The SEC has not issued prohibitions against Chinese companies trading in US markets, insofar they stick to the same rules as other publicly traded comps.