Even if one makes use of DCA Strategy the price of Bitcoin will still keep going up and down after you buy. So I would say this-DCA Strategy doesn't "stop" rather does it even "reduce"  volatility. "What we can say that DCA Strategy does is that it helps spread your buys so you don’t risk putting all your money in at the worst time."

Let's consider this example:

Let’s say a beginner makes use of DCA and buys 0.01 Bitcoin every week for for the duration of 7 weeks. The first and the second week he bought at the rate of $50k, the third and the fourth week he bought at at $45k, the fifth to the seventh week he bought at $40k Based on the example his average buy price will be around $45k. That’s definitely better than him putting all your money in at $50k.

Still on the example, if paraventure the price of 0.01 BTC suddenly drops to $40k and later $35k, his portfolio cannot remain the same, it will definitely go down in value.