Sometimes when they are losing a little in price. I believe that they will get a widespread use in future
I don't buy bitcoins. It seems to me that to buy bitcoins are the only investors, but the instability of the course scares them. At the moment there is nothing that you can buy only with bitcoin. Maybe if it will appear then it will make sense to buy bitcoins. Now everything that you buy with bitcoins you can buy with another currency. Why lose money on the exchange?
Losing money is mostly inexperienced beginners who do not have any experience in investing or are not sufficiently trained. At times of lower prices, you need to buy coins and then sell when the price rises. This is how the scheme of profit is organized in almost everything. Only bitcoin is more suitable for short-term investments.
I also do this scheme - I buy when the price is less and I sell when the price is high. This allows me to increase my capital. Bitcoins I use as a product