I would be very cautious with old coins as new coins and trends offer and to the same but more effectively. Old coins are in top only due to past fame and popularity. Invent something new and people would forget about old in no time. People say they are low risk with low reward, but each day time works against them. If old coins is not something from cmc top10-15, better start thinking about selling it, as with each market dump, it takes harder and harder for them to recover, because people jump out into stables and btc.
Old coins have a large community while new coins have better solutions and tokenomics, which creates an interesting competition in the market. However, from an investment perspective, I also agree that the majority of new coins will have growth potential and generate profits, while the majority of old coins will disappear from the top-cap right after 1 cycle.
Those old coins that survive all have their own positions: BTC, ETH, LINK, ADA, BNB, DOGE all made impressive comebacks in the 2021 bull run while many other old coins failed like EOS, NEO, XTZ, LTC... Therefore, investors should allocate capital to top-tier old coins such as BTC and ETH, then choose more new coins to invest in such as ARB, OP, SUI, APT...