The only thing that hold's Dogecoin is that it is also so resilient as bitcoin is, that's why it stood the test of time.
It isn't clear what you mean by the part that I bolded, but I assume you mean the 'thing' that's kept doge from becoming worthless is the 51% attack resistance. I don't think that's the case, although for miners it might make a big difference. When I think about dogecoin and its amount of coin inflation it always makes me wonder why people use it and how it's managed to maintain its value.
It isn't exactly the most expensive coin on the market but it has managed to trade for at least 20 satoshis for a long time. A more likely explanation for it's longevity is the community it has, which is large and passionate about doge.
Or maybe there's no incentive to try a 51% attack on Dogecoin though, because it's not as popular as the other coins in the alts market. And perhaps Dogecoin design (PoW) is very solid from the very beginning.
Those things are more true in my opinion, though I would think that if a 51% attack could be done that someone would try it just to be an anarchist. And yes, I do think it's design is pretty solid as well. Dogecoin is underrated in my eyes and it's a shame that more customers don't use it to buy things with. It makes for a pretty solid currency.