In the meantime the quantity of bitcoin needed is going down for certain salary levels. I would suspect that a quantity of 4.5 bitcoin in 3 years would be able to support an annual salary of right around $40k per year (even accounting for the ongoing expected debasement of the dollar).
Would that be possible? If he is earning or perhaps say someone is earning around $40k per year and wants to accumulate 4.5 Bitcoin within three year, the person will certainly not be able to accumulate up to that amount of Bitcoin within that time frame, except the person have already accumulated half of the 4.5 already but if the person has not, then their yearly salary of $40k can not buy such amount in 3 years. I believe the person would definitely have some personal expenses to spend on, so after spending on their needs every month, they will not even have up to $40k in a year again. Let's assume they spend $15k a year, they would be left with $25k and such amount can not buy up to 4.5 BTC in 3 years except Bitcoin price is going to drop below $20k. 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.