How do survey websites make money?

Hey guys I was wondering on how these websites who pay you to complete surveys are actually making money and how much profit do they make on average?

I guess the sponsors of the surveys pay them.

In surveys, people fill in their email addresses, age, income, etc : all that data is used in appropriate sales funnels. Remember, it's all about money. You, me, all of us are a product, along our internet usage journey in life, sometimes we are buying, sometimes we are being bought, sometimes we are selling, sometimes we being sold ... It's all about money.
That is why, for legitimately filled surveys, payouts for certain geos are even upto US$3 per survey, this includes the surveys via content lockers.

sponsorships and the ads on the sites

Big companies pay big money to get their hands on personal information from people that might be interested in their products.