Step 1: In a large skillet over medium-high heat, cook the chopped bacon until crispy, about 5-7 minutes. Remove with a slotted spoon and set aside.
Step 2: In the same skillet with bacon fat, brown the ground beef, breaking it into crumbles, until fully cooked, about 8-10 minutes. Drain excess fat.
Step 3: Add diced onion, minced garlic, and diced green bell pepper to the skillet with the beef. Cook for 5 minutes until vegetables are softened.
Step 4: Transfer the beef mixture, crispy bacon, kidney beans, pinto beans, black beans, diced tomatoes, barbecue sauce, ketchup, brown sugar, Worcestershire sauce, chili powder, smoked paprika, black pepper, salt, and beef broth to a 6-quart slow cooker.
Step 5: Stir all ingredients until well combined.
Step 6: Cover and cook on low for 6-8 hours or on high for 3-4 hours, stirring occasionally if possible.
Step 7: Taste and adjust seasoning with additional salt or pepper if needed before serving.