Didn’t the big house in Finland belong to one of their church members? It sort of reminds me of the fundamental LDS groups in southern Utah where no one in the community has a ‘real’ job, yet everyone lives in a giant 10 bedroom mansion. To me it seems like a combination of living frugally, living in countries with good social welfare systems, and the collective support of the people in their religious group.
I have also noticed that the frequency of their videos fluctuates with their spending habits, so I think they do rely on the YouTube income. They only post consistently when they have an upcoming expense. For example, when they went around Europe they were posting every day and probably making quite a lot of money to pay for everything, same with when they bought all those presents and designer clothes. Now they are barely posting or getting any views and are living in a small farmhouse on someone’s rural property, which would be quite cheap. The farmhouse must also be owned by someone they know and they are either paying no or very little rent. No one in their right mind would approve a rental application for a 2 or 3 bedroom house from a family with 9 kids (although to be fair, they do seem to look after the houses that they live in and don’t create any mess or damage, but imagine renting a house that size to some of the other YouTube families). Their cost of living also seems very low with basic home made food, very little clothes and toys, seemingly no or little rent. Even with 9 kids their weekly expenses would be less than a small family with a large mortgage, school fees, car repayments, sports lessons, eating out etc.
Since the toy kitchen has never been seen since that original video, I do wonder whether they kept it or just bought it, used it for the video, and then returned everything for a full refund.