Social blade says they are making £72,000 a year max. Other Youtubers have said the actual figure is usually around half that. Then merch, ads, sponsors etc too that up.
Even £72,000 isn’t much when you consider it’s between so many of them. Even between Chris and sarah it’s not when he spent £20,000 on a van, several thousand on garden furniture and jacuzzi and then the huge mortgage.
I suspect they get a lot more free stuff and sponsorship then they let in and tell brands it’s best to not declare it and make it look organic