"Why do we need new phones because existing phones perform all the same functions as well or even better than new ones!!!"
Do you know anything about how the market works? There is a demand for new coins as a means of making a profit - new coins appear (whether they make a profit or not is another question).
It is possible that in the future there will be coins that are better than btc/eth. cryptocurrency market will grow and develop. Think of it as an opportunity to go to McDonald's today tomorrow to KFC the day after tomorrow to Chipotle and next week to go to a Michelin starred restaurant.
I still don't understand about what u say, bitcoin is a cryptocurrency,it is a decentralized digital currency, did u understand what currency mean ? and you dare to equate it with stuff ?
And also your explanation about how market works its no sense.
There is no demand for new coin, the first thing is project come to the market with a briliant idea,then people looking for it,then they speculate,are this good for investement or not.