one thing that make them popular is they have low barrier of entry, memecoins are often priced low, making them accessible to a broader audience, including new and small-scale investors who might be looking for "the next big thing", but i read somewhere that only 15 out of 1.4 million memecoin is success. that mean to much popularity that some people take advantage of that to creating pump and dump scheme. also influencer lot of them promoting memecoins.
You are correct that the core reason of memecoin is their massive supply and low price which makes easy for every class of investors to buy them. However, meme coins is not a new phenomenon, first memcoin coin DOGE was launched back in 2013, followed by hundreds others and trend is still continues. My firm stance on memecoins is that they are not worth investing in or holding for long term unless they are backed by real life use case.