Depends on the old coin and it's fundamentals The first thing you do when buying a coin is it's fundamentals and development roadmap There are many old coins doing just fine. Am not saying some with good fundamentals don't fail but is a good idea to follow that path cause you will be barely wrong but still choose your coins wisely
Old coins still has the potential but as they said that we should have to check first its website to check its status whether it still active and by there we can see its roadmaps and updates so we can decide to invest or not. Investing old coins without exploring is very risky.
we have to check their developtment progress is it running well or stuck and didnt any product lauched so far. If we analize old or exisiting coins this is the important thing to check , don't ever we trapped in project that die in developtment and nothing to build. Website could not be benchmarket the project still active or not.