$NVIDIA (NVDA.US)$ They all say there is still room for decline, so should I sell it first, wait until it's as low as 180, and then buy it back?

Moving Average (MA) is a technical indicator that uses statistical analysis to average prices over a certain period of time and connect the average values at different times. It is one of the technical indicators used to observe price fluctuation trends and can help investors confirm the existing price trend, determine future potential price trends, and identify signals of impending price reversal.
Here I have selected a stock as a reference.
  $Berkshire Hathaway-B (BRK.B.US)$ 
Here are my observations:
Here I used the 5-day, 60-day, and 250-day moving averages.
Bearish signal
Red circle 2 - After the moving average rises and falls, when the short-term moving average falls below the long-term moving average, this is a sell signal.
Red circle 4 - There is a high possibility that the stock price will fall towards the moving average after a sudden significant increase in the stock price.
Upward trend
Green circle 1 - The short-term moving average is higher than the long-term moving average.
Green circle 3 - The downtrend of the average line is gradually stabilizing, and when the stock price is higher than the average line, this is a signal for an upward trend.
The stock price of Green Circle 5&6 suddenly plunged far below the moving average, with a significant deviation from the moving average. There is a high possibility of a rebound in the stock price.
Basically, the stock price is above the 250-day moving average, which makes it a good buy for long-term investment.
The support price of the moving average can be used as a buying or selling price.
Technical indicators provide an important perspective in due diligence, but they are not always 100% accurate.
In general, investors rely solely on moving averages to make quick and accurate judgments on the best entry...

$Coca-Cola (KO.US)$
are most trading on this stock? or holding it for its dividend in the long run?

$Tesla (TSLA.US)$ chief executive Elon Musk has sold around $5bn of shares in the electric carmaker.
The documents showed that the sale of about a fifth of the shares was made based on a pre-arranged trading plan set up in September. 14 , long before Mr Musk's social media posts at the weekend about selling some of his shares.
The company's shares fell by around 16% in the two days after the poll came out in favor of him selling shares, before regaining some ground on Wednesday.
If you don't know what happened. Go check out the Daily Poll few days before.
Source:
Elon Musk: Tesla boss sells $5bn of shares after Twitter poll