If you have a lump sum of cash that is available, then you have a choice to either buy BTC in a lump sum or to buy DCA; however, part of the common issue is that normal people do not tend to have lump sums of cash in front of them, so one of the advantages of DCA buying and regularly buying is that you are able to figure out a budget in which you can "get into bitcoin" without creating a situation in which you are potentially putting more of a burden on yourself if you put a bunch in at once. There is nothing wrong with bulk buying if you have the amount that is available, yet people can make mistakes in terms of thinking that they need a lot of value in order to benefit from buying into something like bitcoin that allows you to even choose small buy amounts.
Another thing is that you should be considering longer terms in terms of 4-10 years or longer in order to really consider ways to solidly benefit from bitcoin. Sure, you can get in and out of bitcoin on shorter term periods, but you might be losing out on some of the stronger longer-term investment advantages that bitcoin potentially offers (no guarantees of course, even though it still seems to be amongst the best of investment asset classes, if not the best investment asset class currently available).
That's not investing; that's trading... I am not against the overall idea of buying low and selling high, yet with bitcoin you should be trying to consider it as a part of your longer term life rather than getting in and out of it, and then you may well end up fucking up if you are trying to sell in order to make dollar profits, and then if BTC keeps going up after you sold at some kind of mediocre dollar profit, you see that you could have had way higher profits and more options if you had just kept BTC as part of a longer term investment portfolio, such as 4-10 years or longer.
We are talking about bitcoin here. Fuck shitcoins and fuck the idea of crypto currencies that fails to specify what you are talking about. The vast majority of shitcoins (crypto) you have to figure out how to get in and get out, so you better be careful when you are vaguely lumping bitcoin into the same category because it creates an impression that you do not know what you are talking about, at least you do not understand bitcoin if you cannot at least specify and use the word bitcoin, and if you also want to talk about bitcoin and some other shitcoin, at least specify which one you are talking about it and even whether it is worth it to talk about any shitcoin in the same topic of bitcoin, unless maybe you might want to bash on some various shitcoin, then that might be understandable as a reason to bring it up within the same discussion of bitcoin.
You should keep in mind that many shitcoins are affinity scams which largely means that they try to make themselves appear as similar or better than bitcoin in order to confuse people into investing into them.. so if you can at least recognize that bitcoin is distinguishable from the various shitcoins, you will likely start to understand the space a bit better and not be so sloppy with your language in terms of referring to bitcoin and considering bitcoin to merely be a "part of that" conceptualization.