According to your post type only those who sign this forum only invest in bitcoin?.
You may be earning bitcoins weekly from this forum. But those who have other investors how will they invest?
The basic idea of the DCA method is to store bitcoins in small amounts over a long period of time. The more bitcoins an investor can purchase on a regular monthly or weekly basis, the longer his investment will last. Many people are hoarding bitcoins from a weekly source of income and will invest in bitcoins according to their income.
I think not everyone on this forum invests in Bitcoin. But it is a place from which there is much to know and understand. Must understand before starting any business and this one of the best platform where we learning about BTC and trading BTC.
In as much as you are right that every investment requires the right knowledge before venturing into it. Bitcoin doesn't require much from you in terms of knowledge. The more you are wasting time to know have more knowledge about bitcoin before investing the more you are wasting your time and if you don't have a portfolio in bitcoin you are not a holder. Provided you know which wallet to store your bitcoin and how to buy from cex or dex I think you are fine. After all you are buying for the long term, and you can know other things you wish to know along your holding period. Bitcoin doesn't require any professional knowledge before you can buy and hold.
Regarding the DCAs strategy have been designed the impact of trading investing, fixed asset remain regular over time. It's have no limited to BTC but it can apply to any others investment.
DCA strategy is is a method of buying bitcoin at a certain intervals on a regular basis and not for trading investing. Don't confuse yourself with this thing. I don't know what you are referring to as fixed asset, but for the purpose of this thread DCA is a method of buying bitcoin. We are not discussing other investment assets here.