Because the DCA strategy reduces the price volatility to some extent.
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 timeNo, I disagree on this your highlighted statement here buddy, the very purpose of dca accumulating strategy is to make accumulation of Bitcoin very easy and affordable even for the poor, because you can be buying it bit by bit according to your financial strength, and point of correction, their is no worst time to buy Bitcoin, because it's still very cheap when compared to how much the value can rise up to in the future, so what you said in the highlighted words are false.
Additionally, volatility is part of the nature of Bitcoin, so it wouldn't go away all of a sudden because you are accumulating through the dca strategy.
I think you misunderstood @Joeboy or didn't understand the underlying language of what he was trying to convey. I think he meant that investors who maintain DCA method and accumulate Bitcoin will see their portfolio average worth over time with discretionary funds every week. The process of gradually accumulating Bitcoin instead of taking lump sum investment risk.
As the amount of long term buying increases, the UP will decrease as the Bitcoin holdings increase. Spreading buying regardless of the Bitcoin price means that your holdings will continue to grow. A positive aspect of the DCA strategy is that it allows investors of any income to easily continue to accumulate Bitcoins and the amount of money can be of any size.