I agree with you on this. The last opportunity to buy a dip should never be missed. Moreover, the hope of buying a dip often keeps a person in a state of inferiority and despair.
He has to pay attention to the market price again and again to see when the price will drop. At some point, when the market just starts to rise, the person's regrets are endless. Then he starts saying to himself, "Why didn't he buy when he made the decision?" So whenever someone feels that he needs to invest in BTC, he should stick to his decision without taking any outside advice. And if someone is thinking of investing consistently, then he should set the investment date the day after the date on which his monthly income comes.
This will reduce his chances of forgetting.
I don't understand what you meant by (The last opportunity to buying a dip) what you don't understand is that the market would always give investors different opportunities to buy bitcoin cheaper, there are many dips in a full circle as far as Bitcoin investment is concerned so if an investor missed a dip, they can continue doing the DCA then buy another dip if it continues again. Regret would only come if the investors is only using the buy dip strategy cause they'll feel they've missed a buying opportunity and wait all over again for another dip to occur, but why wait? When the DCA is there to help one accumulate periodically and still seize the opportunity the dip brings when it comes. Newbies shouldn't even be waiting for dips before buying Bitcoin, they're yet to accumulate a good amount of Bitcoin therefore the DCA strategy should be their priority.