The biggest expense is securing or owning a building. The heating and insurance are sky high, not to mention the staff and cleaning services that would be required.
Plus, this gig would only be financially supported for 4-5 months of the year.
Any of us running kennels or daycares might have likely done this already, but the numbers would never add up unless you can be open year round with 100’s of dogs daily.
So, wonderful! Idea, but business wise, it would likely fail.