In a large skillet, brown the ground beef and onions, then place onto a paper towel lined plate to drain the excess fat. Into a crock-pot or large stockpot, add the ground beef, onions, beans, corn, green chiles, tomatoes, olives, ranch dressing mix, and taco seasoning mix. Cook on low for 6 to 8 hours, ( 3-4 hours on high) or simmer over low heat on the stovetop for about an hour. Serve with tortilla chips, and your choice of garnishes.