i don't see how that change anything. Yeah they get it easy now, got bigger income, but the whole point is "it not stable". Like trend, it come and go. Even mega big youtober, i see not rare that some wise enough and mentioned they did prepare for that day, so that they can retired if stream.
It makes a difference because one source of their income which has not grown over time (streaming) is what they are pulling back from, while another source (his freelance commissions, editing, and channel) is stated to have stably grown.
Remember, his freelance work was sufficient to pay his bills prior to her arrival in chapter 1, and the story states that her presence saved him money, presumably due to home cooking rather than constantly ordering takeout. For much of the story, even when they had achieved mild levels of internet fame, his freelance work often surpassed the income from streaming. It was a point of mild struggle for him that he was concerned her stream might surpass his own income.
By now, he has a sizable portfolio of video editing in addition to a history of producing advertisements for several companies. It's not the most "stable" career path, but he has shown high degrees of financial literacy and saved up a considerable sum of money by his early to mid 20s. I expect he is capable of making projections on forecasted earnings and expenses.
Notably, he's not aiming to retire outright, but to continue working. His job allows him to watch over the kids without having to hire a nanny or pay daycare costs. They live a modest lifestyle and have the firm backing of his parents, who are well-established and own multiple homes. He is also university-educated, which makes any emergency job search easier alongside his portfolio.