If you have coin A and coin B and their only difference is the scarcity of A, the price of A will be larger in the long run. This means that coin B is not good as an investment & store of value, except for quick profit making.
Bitcoin could be mined for 140 years. It means bitcoin is inflation in your whole life. 5B new doge every year means, it is a very small inflation and the inflation is reducing every year.
Bitcoin = finite
Dogecoin = infinite
Bitcoin = scarce
Dogecoin = abundant
Finite / scarce = better price than infinite / abundant. It's just the way it goes with supply and demand. Basic economics.
Dogecoin is infinite only if you have infinite lifespan.
Scarcity is a good reason to drive price up only when the item has tangible value. When the value is purely speculative, scarcity (and deflation) will kill the trading and it leads to poor market depth and frequent price crashes.
Bitcoin will be dead when it gets fully mined. Doge will keep on marching towards the moon.