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.
What do you guys think?
I tend to believe on the latter rather than on the former. In fact, I don't share your view that Dogecoin is not as popular as the other coins in the altcoin market. One has to simply look at where Dogecoin right now, after all those years that it existed, and realize that unlike thousands of new coins right now which are merely developed for the sake of money, Dogecoin remained at a higher spot, with utility, with solid supporters, and even with a much brighter future than the rest.