Your analogy does not apply. Billionaires are growing faster than anybody else in the global economy. The impoverished are growing slowest. If you want to apply this to your family then the adults would be growing by 15% every year, while your kids growing the least (and your teenagers would be shrinking).

If we take this analogy further, your kids would be the ones working the hardest to bring the food on the table required for this growth, and the adults would consume like 90% of it.