Why do triploids have been unsuccessful in establishing themselves in nature?

Question

although triploids frequently show greater vigor, yield and vitamin content than the diploids from which they arise

Answer 1

Triploids do not produce viable seeds.

Answer 2

at meiosis it is not possible for 3 sets of chromosomes to be evenly divided between two cells. As a result most of the gametes contain abnormal chromosome numbers, which usually lead to dead gametes

Answer 3

They are waiting. Silently plotting for the right moment. You'll see. And when the time comes it will be too late for you to do anything about it!