The idea and concept of the Lump sum buying entails buying right away, it has alot to do with investors decision to invest right away with the available huge amount without considering market condition, maybe you are describing buying the dip instead of a lump sum buying,
I mean, if the market condition is favorable, then yes, 'Huge sum can be invested', this is lum sum investment all by itself.
Investing at a favorable market price is a plus point 'if achievable,' otherwise, it depends on person to person 'depending on the market condition they want to invest in.'
What is your definition of a favorable market? It seems that you are not taking correction, an ideal investors invest at all Market conditions because all they are only thinking about is to increase their Bitcoin portfolio, they can buy through the DCA weekly or monthly irrespective of the market conditions, they can buy through the lump sum if they have a lump sum amount right away irrespective of the market conditions while buying the dip offers buying more Bitcoin at a cheaper price compared to its previous high, they can as well buy too if such plan was made with a reserve funds, you need to understand the difference between buying the dip and lump sum buy.