Best solution: replace it with a table with 3 points of contact with the ground. Three points define a plane; it's guaranteed not to wobble.
This gets repeated a lot. I think if you stop to consider the common case of non-planar ground, you will see that this mathematical factoid isn't actually super-relevant.
(I will concede that it's not trivial to add a fourth leg and make it co-planar to the other three. But this often isn't the cause of wobble.)
(It is conceptually satisfying that once you throw rotation in, the added degree of freedom permits four legs to meet the ground!)
I deal with analogous situations, on a larger scale, all the time. The solution most designers choose is to make the legs adjustable (like via screws) so you get the strong broad support of multiple legs while gaining the ability to deal with imperfections.