Utilities are paid for by use, so that's not really relevant to municipal finances. Even still, the power and water use of an unoccupied residence is obviously much lower than an occupied one.

Property taxes pay for municipal services like parks, schools, and police. The rest of the town's residents get better versions of those than they could afford otherwise. This isn't a very complex idea, regardless of whether you think the town would be better off with more people living within it full-time.