There investors that may not want to go in all at once, they may decide to keep some percentage of there discretionary income and them use the remaining percentage for buying the dip. As per being a low coiner ,it also depends on ones cash flow for someone with a good cash flow management that may have a good amount of discretionary income after sorting out all there expenses may decide not to put all there discretion into buying bitcoin at once they can decide to use some percentage to DCA and the remaining percentage for buying the dips.
Going all in at once is not a bad approach or method if the funds you are using to go all in is from your discretionary income because our discretionary income is meant for Bitcoin accumulation but it will be very disastrous and wrong to go all in using money meant for other expenses that is using money outside your discretionary income. and doing this can be seen as a gamble because it implies that you are using the money outside your discretionary income to buy Bitcoin and then hoping or planning to sell soon if there is little increase in the market and this is why some persons panic and sell at loss because when they have this intention and it doesn't go as planned they will panic and sell.
Well if we talk about long term holding actually I don't see anything wrong about deciding to use all their discretionary income to buy Bitcoin.
Since somehow this is good move especially if they don't have any plans to diversify or explore on other investment since buying lots of volume would give them a chance to earn more returns on Bitcoin.
What I really think will be wrong for doing that is if they put all in on their Bitcoin short term trades since there's really a good chance that they suffer some volatility issues that might cause them to lose their money especially if they get panic easily.