I have a clot in my lower vena cave, that is at least that big. It blocks the return flow of blood from my legs, but tiny capillaries have stretched out enough to allow a rather limited return of blood around the clot. It sure would be nice if I could have it removed. I've been on blood thinner for almost 12 years now, and the extra pressure causes a lot of pain ,with nerve damage I have in my right leg.
I would be concerned about bits and pieces of the clot breaking up while trying to remove it, and getting back to my lungs, or worse, getting hung up in m heart or brain.