She has a mortgage which means she only had to put a deposit down of £80,000. I think she got inheritance after her nan died and they sold the house, also half of her career was at home at her parents, considering what Youtube does for other people (Zoe earned 1.2mil in 2017 alone) she isn't doing that well. I think we tell by how thrifty she is trying to be with the renovations and how she has to wait and time things for when she has money and is going online looking for cheaper versions of things she likes shows that she isn't as well of as she makes out to be, it's almost like she's a normal member of society not a "public figure".
With people like Gabby who had a big influx of money (around Zoe era) and then lose it when people become disinterested it always makes me wonder how much debt they get into, I can imagine they buy things in advance thinking they can pay it off when the next months cheque comes in but the next month could be considerably less money. I think we will begin to see Youtubers filing for bankruptcy and having don't pay take it away appearances at some point in the future, they have to maintain a lifestyle to be appealing but everyone has a sell by date and a lot of people are becoming stale.