Why the thumbs down on John? Dreams are nice but seldom become reality. There are possibly a handful of people ( who must be pretty wealthy) who have visited every country in the world. Slim it down to a functional trip that fits your budget and time or it will always be just a dream. Get real. I have been traveling for 40 years and have been to 76 countries, which is far more than most travelers. Just because there are countries does not mean that they merit a visit..pick those that interest you and work with that. Do you really want to go to Chad?
There are 196 countries in the world, if you count Taiwan. That's 196 weeks. There are 52 weeks in the year, so if would take 3 1/2 years. Do you plan on doing these consecutively?
You know I had a friend just like you. A naive fool who never really achieved or did anything. Always talked about it but it never happened. His dreams were just like yours, unachievable. He always talked about traveling the world, backpacking for years. Last I heard he is still in our hometown. Dreams rarely come true. Make realistic goals instead. That's the best advice anyone will give you.
Start with Afghanistan and then try Iraq and Syria. Great fun!!!