To be honest, buying a meme coin (especially a new meme coin) at above a marketcap of 100 million can be a very risky venture, but then, we all know that buying or investing in memecoins generally Is also a gamble, so, i guess there is really no significant difference in buying them at below 50 million market cap or above 100 million market cap.
But on the other hand again, we all can believe that the higher a meme coins goes in market cap, they stronger it gets and the chances of it listing on a good centralized exchanges increases, and with centralized exchange listing, the chances of such meme coin rug pulling on its investors greatly reduced.
So, going with this analogy, or analysis, I would say that it's actually safer to invest in memecoin with over 100 million in market cap, than below it.