How likely is it that someone will discover my seed? either by brute force or by trying to generate a new one.
A seed has 81 characters with each one having 27 different possibilities, from a simple Combinatorial analysis you can see that the total number of possible seeds is 2781 = 8.7*10115, just for comparisson, the estimated number of atoms in the observable universe is approximately 1079.
This is a unimaginable large number, even each people on the planet trying 10 billion different combinations per second wouldn't stand a chance of guessing your seed. It is much more likely of your facebook login + password being brute forced than your seed.