Maybe it won't go to zero like that chart shows but if there isn't enough young people to at least maintain the population then as the old people die, it will lead to the overall population to decrease, then you also have to consider accelerated deaths due to lack of resources in senior care caused by an increasing lack of young people. 10% reduction seems absurdly low given you can literally see the large difference between the young (0-18) vs the aging workforce 55-59