It is assumed that with trading you can make profit faster than you will do with investing by buying bitcoin either at a lump-sum or with the DCA approach and hold for a long period of years before making profit.
This is not as easy as they say, trading is risky and one should consider their equity/liquidation level before doing that. What if the liquidity is not high? That account will certainly be put to trouble. But in investing, no matter how little or much you have, your Bitcoin will remain your Bitcoin and if it drops so low, one day, it will get back to your striking price and even edge it higher for you to make money without the risk of liquidation.
Also, every investment approach is good for Bitcoin, you may buy low, DCA etc, what matters is for you not to miss out on the slice of the world cake.This is the major highlight here, and I think you are 100% right, the major thing here is buying when the funds is available not based on when you feels right, because by procrastinating and waiting for the dip when you have the funds to buy, you might miss out on accumulating a good stash of Bitcoin due to too much waiting for dips that doesn't always come around, sometimes the price of Bitcoin can rise from where it was which will eventually makes him or her to get discouraged and not to even buy again, so it is very important that once the funds is available, you buy and accumulate regardless of the present price of Bitcoin.
As for trading, it's not for everyone because the risk attached to it is way too much if you haven't masters it, unlike investment in Bitcoin that anyone that has the basic knowledge on how to buy and all that is requires to hold can be successfully in it, once they have a source of income and an emergency fund.