This is the beauty of cryptocurrencies, do your personal research to me is better than accepting chorus answers. Imagine when you made these profit and went ahead to buy back these BNB coins by now you could have be a millionaire if not mistaken, but hope you were able to take little from your profit and invest back into BNB?. Life is all about risk and those who will survive should be those that embark on this journey with risk too, taking risk is good and your ability to manage it make you strong as a survival.
At the point, you share your stories you'll get a lot of opinions each individual with their perspective. You may check that out and later chose wisely. Nobody will actually want to reveal to you when is the best time to buy in or profit out. You will to do your research and decide whether you feel the coin will go up or down. Firstly, we need to decide our mentality, be a trader or just holder. Some are mostly holder but would love to do trade.