There is nothing wrong with a guy who might choose to set aside other funds for buying the dip.  That is not really called diversification, even though it is employing more than one method for accumulating bitcoin that might result in accumulating more cash if the BTC price does not dip.

Let''s say that we have a guy with a $50k per year income, and he is investing $200 per week into bitcoin.  That would be $10k per year and that would be right around 25% of the guys income going into bitcoin investment.  Maybe if he already had been buying bitcoin for a full year, then he has $10k worth of bitcoin and whatever  amount that his bitcoin holdings had appreciated during the time that he had been accumulating it.  There are websites that we can look up the numbers to make sure our hypothetical is realistic... so maybe this guy has 0.14507 BTC after one year of $200 per week.

So then how much is the raise? Did he go from $50k to $60k or maybe from $50k to $55k?  The extra amount or some proportion of the extra amount could be set aside for buying the dip, as you mentioned. I am not sure if there is any compelling case to be made for doing it or not doing it (except that in the case that I described, the guy is already allocating a pretty high percentage of his income to bitcoin investing.. and so hopefully he has already established an emergency fund, or maybe he might need to spend some of his income or the bonus money to shore up his emergency funds).  No matter the case, bitcoin investors can decide these kinds of balances of their income and their extra income.