Are people making alot of money from these facebook groups?

[Matt S]

[Andrea]

Definitely not. The only way that a person would make money by creating a group is indirectly. Say for example a person made a group or fan page of their business and many people became group members or fans, that would likely cause people to purchase things for their business.

[Jenny F]

People are making money yes via blackhat methods, however facebook are clamping down fast & are banning most groups & fan pages

[Jezhug]

I would say they have the potential to make quite a lot of money. It's not hard to completely change the page overnight. A group called "likes to sleep in on Sundays" with a 100,000+ fans could easily be transformed into some sort of business fan page.
The business page would then be able to promote goods or services to a massive amount of people directly in their News Feed.

[Devine Caesar]

Yes

Mainly through affiliate programs

e.g. some shopping sites have affiliate programmes where people find certain products like DVD box sets
Then set up facebook groups for TV shows etc and post the affiliate link on the page then anyone who clicks it and goes to buy the box set the Page owner gets a cut.