Are you saying that anyone who wants a dog should make sure they have say £3k sitting around in case their dog gets hit by a car?
No, but people do need to be prepared for the costs of owning a dog, because it all adds up. I spent well over £100 on bits and pieces when I got my puppy - bowls, lead, collar, ID tag, food, treats, toys, a bed, a crate, blankets, a seatbelt for the car...then add on insurance, vaccinations, flea/worming treatment and puppy classes and it was easily £2-300 on top of the cost of buying him in the first place.
OP also has a dog that's going to need grooming, so on top of insurance you're going to need to add grooming costs - as OP is a first-time owner she probably won't know how to do it herself so that's another cost to think about every 4-6 weeks or so.
I've never had to claim on insurance so far, but he has had a couple of vet visits that cost me around £50 a go - a cut paw requiring antibiotics, another injury requiring metacam - it wasn't worth claiming on insurance as our excess was £120 but he still needed treatment for it. Then neutering which isn't included on insurance plans also cost £130 or so.
I think it's easy to say "well, I can buy insurance and won't need a walker so it won't be that expensive" but in my experience it's all the little things that add up. As an example - ours is a very heavy chewer so we need lots of chews to keep him busy and protect my house. He's not interested in a Kong no matter what you stuff it with, so I spend about £30 month on chews and bones to keep him occupied - and that's on top of his £40 a month food bill and the £26 I pay for insurance, plus the £20 he needs for joint tablets, and the £12 for the vet plan...