Example let's say I want to start investing right now in bitcoin and I have a monthly income of 1000$(it's assumption figures) and I decide that I want to invest about 300$ from that amount into a weekly DCA investment which should be about 75$ weekly invested in bitcoin and then I also had some cash from my savings that I also wanted to use to invest in bitcoin maybe to give myself some kind of head start and the money was about 3000$ and I decide to use 1500$ to invest right away, that is what a lump sum buying would mean
yeah lump-sum payment is complete opposite of DCA, you aware that DCA is the purchasing set amounts of Bitcoin at regular intervals, whether the price is high or low. While lump-summing is the act of going all in at once, just as you just said about the $3000 and all that. Most people that are financially stable may use lump-summing to start their investment to have some good head start in their accumulation without it affecting their regular life style or tampering with their investment. But if an individual who's not financially stable start his accumulation using lump-summing without any proper planning he or she may endup using the funds that are being meant for their emergency (which known emergency funds) in order to execute a nice lump-sum purchase. So such individual won't be able to sustain his self without any emergency funds which may lead to he or she tampering with their investment , and won't be able to execute his long-term plans, selling their investment in an premature state. That is always advisable to invest according to your financial capability, by starting their investment with some nice DCA strategies, so that they can set a proper plan for their investment.