Synthia212

That's likely because there aren't that many countries that employ just soli citizenship rights.

Tell them to look into dv lottery.

Son at 21 yrs can petition his parents and you can be a co-sponsor
in the meantime they can visit for short periods

Lots of other countries don't grant citizenship to members of military families solely based upon their birth in the country where they're stationed.
Not sure about rules in the US.
Your friends should find out whether their son is entitled to US citizenship first.

I think you jumped the gun with "encouraging" them to move here permanently. You do the research first before you give them false hopes of a quick and easy immigration.
1. You can't bring them here. That's not how immigration works.
2. Check to see the son's citizenship status. He may be a citizen or he might not be..
3. If the son is a citizen, he is the best chance for the rest of his family to move here
4. DV Lottery is opening Oct 1 till Nov 3 (or 4) .. They can try their chances while you explore other options.

You can look at the types of visas on uscis.gov.
Generally people immigrate here for work or through family. A lot of good and nice people want to live in the US, but an American cannot sponsor "friends" or anything.
So you can't really help them very much. They could look for a US employer who would want to sponsor them for a job. The kid could go to school but it's temporary and his parents can't come.
Why do you think they need to live here? Venezuela is not so bad.

Seems odd, why?

The 18-yr old son is likely entitled to US citizenship by virtue of his birth on US soil. I say "likely" because if his parents were posted in the US on some sort of a diplomatic visa, that could complicate things with respect to the son's claims to US citizenship. You have to find out the son's citizenship status.

He would use his US Passport.
When he is 21 he can sponsor his Parents to immigrate, takes about a year.
He would need the financials to sponsor them or have a co sponsor.