Can people buying second homes in villages and towns negatively impact the local communities?

Of course. If people can afford a second home, they often have expensive taste but little need for cheap and practical necessities, and in many pretty villages there are several delicatessens but no supermarkets stocking a good range of basics to cook with. The second homers also visit only in summer holidays and at Christmas, so the rest of the year the village is like a ghost world - local pubs can't thrive if a village is half empty and so many close down. The second homers also pay little interest in local affairs, unless something is planned like a new building spoiling their lovely view of the sea, so they don't put money, energy or resources into the community.