Because those just starting out in investing generally only know that buying when prices drop is a good way to invest, this is similar to the Lump Sum strategy, which requires waiting for the price to drop before making a purchase, a common practice when first starting out.
Lump sum is when an investor buys a large quantity of bitcoin at once when his money is readily available, while buying the dip is when an investor already have the money to buy the dip, but he's only waiting for the bitcoin price to drop so that he can activate his buy. Lump sum and buying the dip are not similar. Any investor who is waiting for the bitcoin price to drop so that he can buy bitcoin with lump sum strategy is buying bitcoin with the buying the dip strategy.