Because the DCA method is the only way to invest in Bitcoin,
The DCA method is not the only way to invest in Bitcoin. Because not everyone invests in this way, everyone has different investment strategies so it would be wrong to call it the only way to invest. But we can consider this method as the easiest method because through DCA one can start investing with little knowledge about Bitcoin and small amount of money.
However, the most benefit is achieved by doing a regular DCA procedure,
The advantage of doing DCA in investment means that you can buy the amount of money that you invest, that is, the amount of money that you allocate for investment, at any moment in the market. If the price of bitcoin is high then you can continuously buy smaller amount of bitcoin with that fixed allocated amount and if the price of bitcoin is low then you can continuously buy more amount of bitcoin with that fixed amount.