You are right, in fact, a new user should not go into trading first, because trading is never an easy thing, to survive here you have to learn and know everything about trading first. And for this reason, starting trading first is not the right way for a newbie.
A newbie should start with investing first, especially Bitcoin investment using DCA. If a newbie starts investing in Bitcoin in DCA at the first stage, and decides to keep it uninterrupted for the long term, it gives a newbie a stable entry point, by reducing the impact of market fluctuations.
However, a newbie should start small, and learn trading gradually, and practice on a trading demo account. Success cannot be achieved from trading first, so it is necessary to learn everything before starting trading, and the crypto space should be started from a safe place as possible, such as Bitcoin investment using DCA.
Trading and investment actually have almost the same risks. That's why newbies need to learn firstly before they start trading or investment. I don't think investment will be safer for newbies if they have no proper knowledge. The point is to have sufficient knowledge first before they start trading or investment. Newbies can invest in random coins that may be very risky, it also may lead them to severe losses. However, it will be quite safe to start investment with Bitcoin. But it still requires to know its cycle at least, newbies need to understand the right time to buy and to sell the Bitcoin.
Yep, DCA is quite good way if newbies have limited funds. As long as they start DCA in the bearish season, it is okay to do it. But DCA doesn't guarantee the newbies to gain good profits, it is only the way to collect the Bitcoin. Newbies should know well the strategy in the investment, it is not so different with they way of doing trading.
IMO, it is not a must to do investment first. Newbies can start trading if they prefer to do trading. But makes sure that they have proper knowledge firstly.