Although you are right, we have to remember that the formula is the same in trading and investing. That is, invest and trade with the amount of money you can afford to lose. Only when you are able to lose the amount of money will your energy and inclination towards investment work, but you will not be emotional. Many times it is seen that people are afraid of investing, but instead of being afraid of investing, they participate in the investment with the money that they can afford to lose. For example, if you can afford to invest $10, you can invest from here if you are not emotional about losing it. Never invest by force but invest as much money as you can afford to throw away, you may make a lot of profit at one time and may also lose. You should invest only the amount of money that you can afford from your point of view consistently, or else you will force yourself to never invest. However, if you are investing for long term then it must be sustained and once you can get huge profit from it then hold it.
Back to the basic concept, we come here not to lose, lose funds, the cause is from ourselves because we want to double the investment quickly and hope that in 2 or three days the investment value we trade can produce and increase from the initial capital. The reality is that most of them are big zeros, especially if market conditions are uncertain and their movements change. I guess buy and hold it for a long period of time, That's probably the real thing whether to use DCA or want it all at once.