You're focusing on one side of the supply-demand graph. Immigrants increase both the demand & supply side, they require more jobs but also the increase in population increases demand for more products and services. There is no fixed amount of jobs in a country.
I do agree if a country were to let in 100 million immigrants over night or some insane number that it would mess up the economy, there is an upper bound to this.
You're focusing on one side of the supply-demand graph. Immigrants increase both the demand & supply side, they require more jobs but also the increase in population increases demand for more products and services. There is no fixed amount of jobs in a country.
I do agree if a country were to let in 100 million immigrants over night or some insane number that it would mess up the economy, there is an upper bound to this.