It's not about career prospects. It's about joy and about learning a way to structured thoughts which few other activities can provide. A computer can't be argued with or tricked. It executes instructions. You can't beg it to be nice, you have to actually fix the bug. It won't betray you either. This very strict cause-and-effect property is a very important lesson that too few members of society have understood.

You may wish to show your kids something like Scratch or even just drawing pictures with Python's turtle library, just to get a feel for their interest level. If they figured out how to install games and stuff on their own, they are good candidates for programming, provided they are interested. Most importantly, you cannot rush it. They will become interested in programming (or anything else) if and when they are ready. Any age is a good age to get started. I have much respect for folks who discover programming during middle age or older.

Oh, and like the other commenter said... worry about their career prospects later. Right now, for them it's about having fun.