Should I intervene in this situation?

I know two teens from a wealthy extended family who are spoiled. Everyone at home spoils them rotten, they are socially immature and VERY manipulative due to no boundaries given. They are both 15 year old twins (boy & a girl). I interfere if I catch them bullying or being unfair to someone. Their parents buy them absolutely everything they want. They have the latest iPhone, laptop, and hot tub in their rooms. They don't see the value in friendships, just getting material items is the most important thing. Even my daughter doesn't want to talk to them because they constantly label anyone who is not wealthy as "peasants". I occasionally witness them bothering other kids - and sometimes they don't even realize that they have that snobby attitude or they have rude manners. I don't think receiving a scowl from an adult who witnessed you bullying someone will work because the MAIN problem is the parents. Kids who were never taught that doing certain things are bad will do harm without even knowing. Especially in the big cities, a lot of parents don't believe in the "it takes a village" concept and will be upset if anyone steps in. However, I can see that they are struggling badly due to their parenting.

Yes

If the children are truly struggling, they will be open - in their own way - to listening to sources other than their parents. You do not need to "intervene" and if you do, these people will wad you up like wastepaper and throw you away.

Let the children come to you in their own time, or to whomever they will. Like kids always do.

It's a shame that these teens are being brought up this way. As you state, the main problem is the parents. Parenting is a verb and simply giving your kids everything materialistic that they desire yet not teaching them important skills in life such as manners and respect for others is negligent parenting. These kids will grow up to be as they already are being: self-centered, rude adults. I do not know your relationship to these kids but unless you are an aunt/uncle or close relative, I do not think it is really your place to intervene too much but there's no harm in doing as you have been doing and saying something to them if you witness them bullying or being unfair to others. Again, depending on your relationship, maybe it would be best to talk to the parents of these teens and tell them some of the bullying behavior you have witnessed. The parents may not do anything but maybe they are not even aware.

Maybe you should tell their parents what theyve been doing

This is not your family so it's none of your business.