Bitcoin is preferred over others because it has a positive history where when the price has dropped, it always recovers, and sometimes, it exceeds the investor's expectations because bitcoins price reached a new ATH just like what happened in the last bull-runs. right now, they have high trust and they are always buying some bitcoins whenever the price is low because of the past history where the price will always recover, they don't feel any doubt rather they are just relaxed and steady. compared to the other altcoins, some are always failed and most of the time cannot recover their old high price and continue to fall until it no longer in the market.