This is only suitable when applied to Bitcoin, because when you apply it to altcoins or tokens you will never know what the fate of the project will be in the long term, even though they are still available on CEX or DEX but they can turn in just one night into a scam project so even if collect it at a cheap price, it may still have no value when the project turn into scams.
Beginner traders would be better trading in Bitcoin compared to altcoins because if there is a decline they can change to hold it and wait for the price to recover and go higher, whereas altcoins will very likely never recover, we can see on CMC and only altcoins that are stable and listed on major exchanges with high trading volume that has a chance to recover or even reach the latest ATH the rest is just rubbish.
It is not necessary for a beginner to start only with Bitcoin, if we are talking about trading, then it can also be other coins, and to avoid such a case as you described, you do not need to invest your entire trading deposit in one coin, then you will not receive such significant damage if this happens to only one altcoin. Beginners often choose altcoins because they are more volatile and this gives them the opportunity to grow their funds faster, or they just think so.
Both Bitcoin and other altcoins are almost equal when it comes to trading because all other cryptos including Bitcoin fluctuate in price and no one can guarantee or accurately predict when the price of any coin will rise or when the price of Bitcoin will rise. So all coins including Bitcoin are risky when it comes to trading. But if you are thinking of holding then Bitcoin is definitely better because long term investment is more likely to profit from Bitcoin and it is more guaranteed. I am not giving financial advice to anyone. I only mean that Bitcoin has made history so far