No, the 30 Million estimate is just too low. Hasbro/WOTC does not publish specifics, but they do release it in press releases and various reports. Still, D&D doesn't make the kind of money their card games do, or did.
However, after subtracting various values from various reports and news releases, WOTC's D&D brand all by itself makes about $70,000,000.00 per year. Well, as of about 3 years ago, when I last cared to research it. That is in sales, not profits. I couldn't find consistent profit numbers. However, knowing what I know about profit margins, their profit on that $70 Million would be below $10 Million.
So no, the D&D brand for WOTC is not very profitable. Which is why they like their card divisions so much. Those profits were around 20% of their sales totals. They may have been as much as 30%. Where as the D&D brand was about 14% profit on their sales.