This would be possible if the person is earning way higher than $60k per year or luckily Bitcoin price drops down to $50k or they would have to increase the yearly intervals they have set to accumulate the 4.5 Bitcoin.
I am not going to presume that the bitcoin price is going to drop... sure it might, but we should not be making our plans based on things that are out of our control.. Yet, each of us should be able to figure out how much of our income that we can put into bitcoin and then therefore how much bitcoin we might speculate that we are able to accumulate through our various accumulation strategies.
In addition, the presumably possibility that price will drop is a 50/50 chance but however, focusing on price drop to accumulate is basically if not the same thing with wasting to try to find the best entry point. hence it's more of a better opinion to figure out how much you're willing to sacrifice for bitcoin within your discretionary income. if we have enough it's even more advisable to buy aggressively as long as we can afford it without tempering with our daily expenses which will lead to deeping hands into our investments.
I'm assuming that you are referring to buying the dip and if that is the case, it's obvious you are missing an important ingredient of that method of Bitcoin accumulation. Buying the dips does not mean sitting idly and waiting for price to drop neither does it forbid the person from apply other methods to buy Bitcoin while still setting aside some funds with which to buy should price drop below a set target. You can buy with the DCA method with some portion of your capital and keep a small portion for buying the dips. This is what I understand as effective way of buying the dip.
If I have $5000 to invest in Bitcoin over a space of 6 months and within this period I expect that price may correct a little before continuing the upward movement, I can decide to allocate $4000 into DCA purchase spread across the 6 months and then keep the balance of $1000 to buy the dip should I see the correction. This is not a bad way to proceed and is how I understand buying the dip to mean.
If I have $5,000 right now, I will not invest all my money in Bitcoin at once, but I will divide this $5,000 into several parts and invest it continuously according to that. That is why I will not invest all my money in Bitcoin at once because if I invest at once, I will have an investment at any point in the price, but when I divide this $5,000 into multiple parts and invest it, it will be seen that I will be buying Bitcoin during many positive and negative changes in the market, which will result in my investment not being much more. Basically, I can directly consider this investment as a DCA investment strategy. In the case of DCA investment strategy, the issues are similar. In the case of DCA investment, investors usually invest continuously based on their income. In this case, when I have $5,000, just as I will invest continuously from this $5,000, I will also separate a part of my income so that when I finish investing this $5,000, I will continue to invest continuously again.