Are you sure? If we assume you saved 10 USD per day on food, that means you can invest 3,650 per year. If you do that for 50 years and assume 5% interests, you end up at 844,182.20 USD.
Inflation has been ignored to simplify it a bit, but it works in both directions: your money is worth less than today, but over time, as food is getting more expensive, you also save more and more money per day.