Rahu in the 11th house is generally considered a powerful placement for sudden wealth and massive gains. However, it comes with a strict physical warning from Lal Kitab.
Rahu represents smoke, toxins, and sudden, incurable diseases. The 11th house is the house of gains, but it also aspects the 5th house (which rules the chest and lungs). If a person with Rahu in the 11th house starts smoking cigarettes ("cigarette piya"), they are directly feeding Rahu's toxic energy into their lungs.
Dr. Rishi Rohit Sharma warns that for this specific placement, the lungs will deteriorate much faster than normal ("jaldi jawab diya"). The wealth gained by Rahu will be spent entirely on hospital bills.