Professional traders use technical analysis. These are based from combination of charts, indicators and candlestick patterns. Based on daily candle stick pattern and RSI, BTC is already at oversold zone when it hit 8K yesterday, with this I expect it to dip to around 7k and should have a bullish run in the next week or so.
disclaimer: I strongly deny that I am a professional trader
https://bitcointalk.org/index.php?topic=2873063.msg29503403#msg29503403or
https://www.investing.com/currencies/btc-usd-technicalHve a look at these, regarding the technical analysis ! so most of them say that on a monthly basics .. the signal are Strong Buy