There's no investment without any risks attached to it, managing the risks depends on the investors, like you said most people invest carelessly without understanding the market and all that, but that happening in bitcoin the chances is low. As long you can develop the habit of long-term investment. Alot of people bought bitcoin back then when bitcoin created the ATH of the price range of $60k. But still didn't sell even when bitcoin experience a great dip back then but they keep holding and using the DCA method to keep buying the dip now the price range is $40k they would be in great profits now due to the DCA strategies. While about comparing bitcoin to other altcoins bitcoin has already surpass them all though they are still good altcoins you could invest on.
A lot of those who bought that type might be lured by the news and hype of the bull run of 2021. Most of those people joined Bitcoin because they heard it was making people rich, so they rushed and bought hoping to sell and make money quickly. When the price reach the peak around $69,000 and started retracing, some were advised to hold more that it would retrace. It kept dropping and taking longer time and the assurance of retracement became ineffective, so most of them sold at loss and left. It may not be all of them that sold but it is very rare to see those who started their Bitcoin buying around that time that is still holding till date.
Starting to invest in Bitcoin is something one should have clear intentions and plan for before starting to avoid running into troubles. It is good that a lot of ideas have already been discussed here, those who are still not clear about certain things should just do little reading.