They should realize that the best time to enter the market is when the low is under $20k, but it's also not bad if they want to enter between $27k to $28k. In fact bitcoin is still -58% from its last ATH, so I think it is good to invest now instead of waiting for big bullish. If you have any doubts, you can buy with DCA.
If you buy at a price 10-20% lower than the current price then the purchase allocation must be lower because market prices are unpredictable, so make sure we determine the highest purchase allocation on a correction of more than 50%, I have applied the investment DCA method above, so all investment decisions depend on market analysis according to each other's opinion, make sure you invest money that is not related to any needs except for crypto investments in the long term