sometimes I think if you look at the amount of token supply in such a large amount that trillions and trillions after the project runs several months or years, the token will be burned, what for if you make tokens with a large supply, but will be burned, ...?

Agreed, i m not seen seeing the main point to create a big supply of token. I just see that a trick that has already made by the developers. We can take a look at pundi and how it was always creating more and more new tokens and then burned it. It looks like the reason for the creation of more supply totally non sense. Some developers said that it's to fit the development of the platform or even to get more adoption.
The total token supply is indeed static but it doesn't mean we need to create more and more supply like some crap projects that even create multi-billion supply which didn't make sense.
They are for rewarding the token holders by increasing the price.
For an example, look at BNB, the exchange binance allocates a portion of it's profit to buy back BNB from market and burn them to decrease the supply quarterly.
It's a direct way to make the investors profit in proportion to the profit of the project.