Sometimes but sometimes you need to check and observe the situation because for instance you may buy bitcoin for a high price and selling it low because of the market price. When this is done, then I will say you've lost somehow but when you buy bitcoin when the prices are low then hold and sell later, my friend, you are gaining more than you invested.
Ideally, it is better to buy Bitcoin when its price is low than buying when its price high, but that scenario just does not occur frequently so it is hard for people who are just starting. It is good to buy whenever as long as you are financial capable just so you could get started with your investment.