To become the biggest octopus in the world and eat everyone, you'll need to follow these steps:

1. Start Small: Begin as a tiny octopus in the vast ocean. Your initial size won't intimidate anyone, but it's the perfect starting point.

2. Grow Strategically: Consume smaller marine life to increase your size. Focus on fish, crabs, and other small creatures to build up your mass gradually.

3. Master Camouflage: Use your natural ability to blend into your surroundings. This will help you ambush prey and avoid larger predators while you're still growing.

4. Expand Your Territory: As you grow, explore new areas of the ocean. Each region might offer different types of food and opportunities to increase your size.

5. Tackle Larger Prey: Once you're big enough, start targeting larger marine life like sharks and whales. These will provide more significant growth spurts.

6. Evolve Your Skills: Develop advanced hunting techniques and possibly even learn to manipulate your environment to your advantage.

7. Dominate the Ocean: With your increased size and skills, you'll become the apex predator. No creature in the ocean will be safe from your grasp.

8. Emerge on Land: To truly eat everyone, you'll need to venture onto land. Adapt to terrestrial environments and use your size to overpower humans and other land-dwellers.

9. Maintain Your Reign: Keep growing and consuming to stay the biggest octopus. Continuously adapt to new challenges and threats.

Remember, becoming the biggest octopus and eating everyone is a monumental task that requires patience, strategy, and a lot of seafood!