Percentages are interesting metrics, but real dollar values are more important when you're talking finances. If profit is revenue is $100 and costs are $1, you've got a huge profit margin, but it is unlikely that you can grow that revenue to $10m. If you have $5m in revenue and $2.5m in costs, your profit margin in percentages is lower, but you have the basis for a company that can reinvest profits to increase revenue growth.