We have a bigger house than we really need, many bedrooms, multiple reception rooms, lots of outbuildings.
I regret it sometimes because: it's really cold, something is always breaking/going wrong, nothing is ever simple to fix due to being listed and stupidly complex boilers and electrics, you could throw £200k at it and you wouldn't notice the difference.
If we had spent half as much we would still have a lovely house but my DH pretty much insisted on this one.
I also think that if we had a smaller mortgage I would be more comfortable. I could never hope to earn enough to pay the mortgage, and so if anything happened to DH we would have to sell ASAP.
That said, it is truly beautiful and in many ways a privilege to live here.