some people that wants to buy using the lump sum strategy sometimes also wait for a dip so they can buy.
I guess that you are misunderstanding buying with lump sum and buying at the dip. When you are buying with lump sum, it means that you are buying right away irrespective of bitcoin price at that moment. For instance, if you are paid bonus at work and you use the money to buy bitcoin immediately is called lump sum because you don't need to keep the money and be waiting for the dip before buying.
I don't see any much misunderstanding about what @SuperBitMan said because there are still investors that has kept a huge amount of money just to wait for a DIP so that they can buy at once which is the lump summing that we are talking about but it is not too good for any one who wants to lump sum to wait for a DIP before buying Bitcoin since the price can skyrocket further while still expecting a DIP in order to lump sum.
Buying at the dip is when you keep some funds and wait till bitcoin price dips before buying and that is not a good practice for a no coiner or low coiner to use without his DCA going on regularly.
Yes your explanation about buying at a DIP is okay but buying at a DIP is mostly for those who uses the DCA strategy and they have reserved funds that they can use to buy Bitcoin at cheaper price when a DIP occurs.