I have one thing going on in my mind for quite long i.e. DCA is also a form of lump sum investment. Like if a person is investing 10$ per week then he is like investing a lump sum of 10$ in week one and then a lump sum 10$ in week two and so on. DCA is also a kind of accumulation of Lump Sum investment that are made over a period of time. It's my own interpretation, it may or may not be correct.
You also have a valid point that anyone who invested a huge money several years ago and is ignorant about Bitcoin that he didn't invest at later stage, such are just hypothetical assumptions. The person who is inve. sting a lump sum money into bitcoin is well aware about Bitcoin and will continue to invest in Bitcoin over a period of time.
Okay, so you're saying DCA is like making a bunch of small, separate lump sums. Kinda true, but it's different. Lump sum is ONE big investment. DCA is many small ones, spread out. It's like the difference between dumping a bucket of water all at once versus slowly pouring a glass at a time. Both get you water, but DCA is less risky. Anyone who put a load of cash in Bitcoin years back probably knows the deal and is likely still adding to it, just like you should be. It's all about stacking sats, whether big or small.
Your context is wrong and I think he is right. Lump is the same thing like gathering things together until it becomes one big thing. How does that relate with DCA? When you buy $1 dollar worth of Bitcoin every day for 365s, you will be having different inputs(unspent transaction outputs), they are combine to give you a sum of $365 but you wouldn't see this inputs until you want to spend it, with his context of lumps DCA, he is right because you accumulate small amount of Bitcoin together until you have enough of your target.
Microstrategy is one perfect example of person that is doing DCA every day, they have a public wallets address on watch. You can use Akram platform to check the history of their DCA, the wallet address has been receiving Bitcoin since 2012 and till date, the wallet still receives more Bitcoin and he they don't have any precise day of when they are going to sell a single On my way. Blackrock is another example of wallets that is DCA Bitcoin everyday because they having vision and goals for Bitcoin.