Math time! Let's say you donate $1000 to continuously provide meals.
On average, in the past 30 years, the market grew 10% per year.
So after 1 year, that $1000 grows to $1100.
Part of the profits are taken to buy the meals, and the other part stays together with the initial donation to continue multiplying and producing more meals.
For example, we buy meals for $50 and reinvest $50.
So, we start year 2 with $1050, and after another year, that grows to $1155.
Now, we can distribute even more meals!
Every year, more and more.

This is called compounding and it's one of the most powerful traits of investing.
If we repeat this process over and over again, during an average lifetime (77 years), you provide ~33x more meals than with your traditional donation.
So, instead of immediately donating, for example, 500 meals with $1000, your donation gets invested and provides 15,000 meals over your lifetime.