After living in so many different houses while growing up, I figured there was little you could do to improve the situation once a state of the art home had become leaky enough to present temperature problems.
You assume that there are just too many open holes either inside the attic or within your own walls that it would be foolish to address the issue with any sense of urgency.
Of course, I understood that windows are a sizable factor for a home’s energy efficiency, and since it’s obvious to anyone with a brain that most of the time they can be swapped out and upgraded—that means there is clearly something a homeowner can do to mitigate a drafty house. And of course there is the weatherstrip foam that you can put inside the creases of your doorways leading into your house. This eventually becomes a pretty big factor in addressing drafts and terrible insulation. But, there was one example I saw recently that entirely surprised me. While learning through service tips for central heating and cooling systems, I spotted a post about getting your air duct resealed from the inside out. You could have an Heating and Air Conditioning tech coat the inside of your ducts with an adhesive that hardens and fills any air gaps, leaks, cracks, or holes. A different product called Aeroseal is sprayed inside of your ventilation system and bonds to the inside surfaces of the air duct. The minute plan costs more money and requires more product to achieve the same results as having a professional do it with his own hands. Regardless, if you have drafts due to leaks in old metal air ducts, this could be a gamechanger in addressing your home’s energy efficiency.