We have an exception to if we are interested in going all in at once with our investment, this could be only possible when we make the necessary research on the previous performances of the market and the coin we are having in mind, then compare the past to the present and if you could speculate something out of it, whereby it's profitable to buy the dip and invest when the market is extremely bearish, in this situation, you can go all in at once and invest, but never make a mistake of investing on anything else aside bitcoin.
It is therefore mostly advised that when choosing a particular pattern of accumulating our bitcoin asset to hold, we should make use of a pattern that best serves our interest, using DCA or going in at once with the market when it is dip, buying and holding at the bear season is profitable enough provided that we can hold.
No amount of research you make on any coin should make you go all in because to hold you must follow the steps outlined in this thread we are following. Besides, our focus is on Bitcoin on not other coins. Even though we are discussing how to buy and hold Bitcoin, it is not wise to invest your entire money on Bitcoin. Here we encourage people to invest only amounts they can afford to hold for long and still have their peace, live their normal lives and even have some reserved funds.
Furthermore, the term "go all in" is popular among those inundated by hypes of shitcoin. They usually throw caution to the wind because they want to become rich overnight. After reading the beautifully exaggerated whitepapers and studying the seemingly roadmaps and price projections, they are usually convinced they are in for quick wealth. Most of them only find out that they have been fooled when it is already late.