On how we might preach the whole process to be, investing by lump summing isn't suitable for a beginner, how should he know at what price is comfortable to purchase, even a well knowledged investor might slightly enter from a wrong position which may hinder the progress of his profits.
Every strategy is well suitable for every beginners, so I wouldn't discriminate beginners in terms of utilizing the strategy, perhaps I think your advice should be that if beginners does not have an additional plan or having a good source of income that would easily backed them up if they Lump sum they should not go into it but if they have there is nothing wrong in adding more fraction to there investment portfolio while DCA is still there major target, we shouldn't feel or have the mindset that all the beginners are not financially stable because on the contrary there are so many rich people who chose to diversify there funds into Bitcoin so perhaps as they are doing there DCA whenever any opportunity come out for them to Lump sum they would always buy more.
As a beginner there is yet a low level of understanding on how the market flows, anything could hinder one's success of accumulating a good amount of Bitcoin, relatively with how much funds the person has invested already. Beginners are expected to play safe, even those who understands and also are wealthy to lump sum preferably choose to DCA rather than alone lump sum. Both can be done in the whole process of accumulation but it is not advisable for a beginner to prioritize the root of lump summing other than DCA, wrong timing to lump summing is one big effect as to yet a beginner.