There's no supply cap on Dogecoin, and over 5 billion new coins are made every year. 

This means to drive the value up, the memes must increase in quality since there is no value proposition with the supply. The memes for Dogecoin are good, and it caused people to make a lot of money who know how to ride the meme waves. But here's the catch. What if Elon tweeted: "I realize now that Dogecoin has security concerns." Or what if he tweeted him stomping on an ant, and the ant's face was the Dogecoin logo?

A meme lord who can post a bad meme to kill your investment is musical chairs because the investment will collapse when the memes aren't cool. So for Dogecoin, the memes must continue to satisfy the increasing supply of it (over 5 billion per year). That's the investment thesis.

The second the memes stop, the music does too. And if you're not in a chair, you're fucked.

Comparisons: 

Doge mined/year: 5,000,000,000

BTC mined/year: 328,500

BTC mined/year (after 2024): 164,000