"unless your commute is £2 each day on the bus"
Well, I don't drive, so my commute is actually £4.50 a day on the bus unless I get a lift in and walk home. (Just walking home would not be a saving - I need two buses to get to work, so I'd have to buy a day ticket anyway - and I can't really walk both ways as it's two miles and all uphill to get there.) I've also at no point said that I wasn't saving money through WFH so we're not actually arguing here.
You're also overlooking some of the negative effects of WFH, although you do touch on them. It's nice to have a six foot commute from my bed to my desk, but it means I'm spending 16 hours a day in the same room - even more, if I want to use my own PC in the evening, as it and my work PC are hooked up to the same displays and peripherals. I don't have a wife or kids so I'm spending much less time around other people, and I know it's affecting me negatively.
How did I manage before? Carefully. I don't have a car to operate or maintain, I don't drink or smoke, I don't go to restaurants, I spend minimally on clothes, and barring my annual trip to a trade fair in Germany I don't go on holiday. Before WFH I was able to set aside a little each month; with it I'm able to save more, but I expect the cost of living crisis is going to put me back to where I was before long. If I had to start paying to commute as well I don't think I'd be underwater straight away, but I'd have to make cutbacks to what is already a fairly spartan lifestyle.