a lot of people who buy bitcoin because maybe I think they can still benefit from bitcoin just imagine you make this thread in 2013 while now in 2018 you must regret for selling bitcoin too fast.
That is what purpose of why we are still buying bitcoin and other cryptocurrencies, to benefit and gain profit out of it. In only you had bought bitcoin from 2013 and hold it until now then you are one of those crypto millionaires that benefited from bitcoin.
Yes you are right, people can use the volatility of the market in order to earn more profit, the price of bitcoins today is currently decreasing and that is the reason why we should invest today because we will surely earn a huge amount of profit when the market price goes back to normal.