Many years later this shitcoin still exists, and within the top 30 market cap.
We know it's meaningless and has no real advantages to Bitcoin but... the majority of people don't.
The majority of people know very little about crypto, and they never want to learn. Learning new knowledge is mostly a burden to them. And bear in mind that most people don't judge things by content and quality, but by appearance, and often with their their own prejudice in an emotional way.
Dogecoin early promoters painted the (false) image that "Bitcoin is used by criminals but Dogecoin isn't, so DOGE saved the crypto reputation, thus better than BTC". And the Doge brand seems to be more cute than Bitcoin's "golden coin". These superficial appearances are enough for many people to prefer DOGE to BTC, emotionally.
With these adopters existing, DOGE will keep flourishing. It's people's belief which gives money / cryptocurrency its value.
For DOGE to go away, there needs to be some dramatic events such as a major hack which reveals its big security flaws, or if it turns out that criminals use DOGE too, which tears apart its false "cute" image.