If we talk about meme coins, indeed the two coins between Doge and Shiba can be considered successful,
but if you look at it as a whole and compare it with the top three coins you mentioned, of course Doge and Shiba have a greater risk,
it is too risky to hold meme coins long term and better to trade short term
Don't know if I will agree when you say the two meme coins are successful because to me a successful coin means that it deliver its purpose and all people embraced it. IDK if what is the purpose of meme coins, maybe they promised to be a better payment system but they are not successful with that because people don't take them seriously and use them on a different purpose. Not all people likes them too but most hates them.
Shiba and doge coin are only lucky because they are not yet delisted on the exchanges up until now. There are still risk even if we invest in the top 3 coins mentioned above and their risk can depend if how much you invest or if you have a lack of knowledge on how crypto investing/trading works.