I have had cats since I was a child. As a family we bought kittens from the local pet shop, had kittens from people whose cat had had their own and we took in a stray. As an adult I've adopted via a charity and also had kittens from a pet shop. Not one of those cats was problematic in any way - all had different personalities, some were more lively or friendly, others shyer. The one who had been a stray was very sweet but nervous around our other cats. Our latest 2 were sisters - very loving with each other as kittens, mostly ignored each other as adults. The one we still have is almost 20 and still going strong.
We didn't pay up front for medical cover for any of them but I possibly would if we now had another cat.
We always have had a cat flap - never lived on a main road but near to them. Only one got run over (when I was a child). Others all lived to a decent age.
I just bought supermarket food until our current cat was diagnosed with kidney disease - she's been on a diet of renal food for years now - and also has a thyroid condition for which she has daily medication.
Neutered females are home lovers - they don't wander as far as neutered males. Our latest two barely left the garden, the one we still have only goes to the garden now to sunbathe. We've had a litter tray for the past few years due to our cat's sister being unwell and needing to keep her in, and we've kept that going for our remaining cat. Otherwise we only used a litter tray when a cat was unwell or when we left them at home for a few days and had someone coming in to feed them.
Unless you're very short of money, cats aren't really a big expense other than when it comes to vet bills. So having pet insurance makes sense, though over the years could possibly add up to more than the one off payments we have had to make.