The thing is, as Bitcoin already proved its ability and if you trust it then it already gave you lots of options to buy with cheap, like after end of provides bull season, bitcoin was down for a year maybe $16k something. But where were these investors who wanna buy Bitcoin now? So you should buy that time. Now its flying and already get huge up. Now its risky. Nobody knows if it going to hit $100k or down to $40k again. Even whom who buy at ath price of $72-74k price, are in loss currently. But if they buy now then they can avarage their buying price and get rid of losses. Bitcoin is valid but don't it also follow some criteria. Don't buy or sell blindly. Although now I'll take risk for buying. If it go down, will buy again to avarage the price.
Your naratives shows that you are yet to figure out the true potential Bitcoin holds and how to go about it, yeah in as much as those that invested in Bitcoin earliest days must have benefited a lot, it doesn't make much of the difference with those buying now if only they can hold for longer period of time of about 4 to 10 years or more, buying Bitcoin when the price goes down can be good as it gives the opportunity of buying more Bitcoin at a lower price compared to it's previous high but you don't have to wait for a price drop before you buy, as you don't know if you are going to see the drop you are waiting for, because Bitcoin could go higher while you are waiting for a price drop, with your dca strategy you can buy Bitcoin irrespective of the price point either weekly or monthly according to your financial situation on different intervals which makes you to be in the market on time without any forms of timing the market, while making other arrangements for buying when there is a price drop, your consistency with your dcaing is very important as it takes fewer and fewer of Bitcoin to have a sizeable worth of Bitcoin which you will benefit in the future time.
You are absolutely right mate, even if we invest now and allow our investment stay longer time or maybe years we are still going to benefit like those old investors provided Bitcoin skyrocket so high above our investment price. If anyone wants to enjoy Bitcoin like those old investors then, one should have patient and keep accumulating more Bitcoin maybe using the DCA method just as they have said above and if you are able to accumulate more of it, it can be possible to gain profit more than those old investors during their time if the coin value appreciate excedenly.