It's not a bad thing to decide all in BTC, especially for newbies who don't have good analytical skills
It is no problem focusing on BTC only, but why don't try more efforts to get higher profits in altcoins? Newbies can learn analytical skills gradually, someday they will master it. If the newbies already master the analytical skills, it is better to try investing or trading altcoins also. We don't miss the opportunity to gain bigger profits. Come on, be smarter!
maybe based on risk management and trading plan holding bitcoin give more certainity in profits potency if compared with another cryptocurrency. sometimes investors only hold single assets but mostly in major coins such as btc , ethereum and bnb. actually it should not be problem due risk analisys and risk acceptance. altcoin maybe more suitable for experienced investors not for newbie due possibility trapped in shitcoin.