It is normal to get disappointed with other crypto coins because there are thousands of coins in the market where many coins are scams. However, Bitcoin is the only coin that even if the price of the coin is seen to fall a lot, it recovers very quickly and Bitcoin controls the entire crypto market. Bitcoin always follows a circle due to which it can be trusted very easily and even a new investor can easily track the movement of Bitcoin by looking at the past graph. So I agree with you that even if someone gets disappointed with other crypto coins, no one gets disappointed with Bitcoin. Bitcoin never disappoints anyone if he/she believes in Bitcoin and makes a long-term investment.
Only someone that do not have patients will sell their coin because of the fear of losses. Even though Bitcoin depreciate, it will skyrocket again in no distance time. However people that sell when the market is low are short term investors, a long term investor will not always keep an eye on the market, they might only do so when they want to buy and after then they forget about the market, may be ones awhile they chack but they don't get panicked to sell when market is low.