Your question addresses one of my "hot buttons"--whether an offer will be considered "insulting." And, to your credit, you really clarified what you meant in your comment below.
Still: Never worry about whether the seller might perceive an offer as "insulting." One seller might be delighted to accept an offer 25% below the listing price. Another might be "insulted" at an offer just a dollar below the listing price. You never know.
More important, you shouldn't care. As you note, you're not in a popularity contest.
Further, is the seller concerned about insulting you? Of course not. If your scenario is correct, he's priced his home way above market. What's he take you for: A fool? Now, that's an insult. Is he concerned? Of course not. Further, let the seller be insulted by all the people who took a look at his property and decided to not even make an offer. You at least would have the courtesy to make an offer.
Point is: If you don't make an offer, you won't know whether or not it'll be accepted. You can sit there all day wondering. And many people sit there in terror out of fear of "insulting" someone they don't know by making an offer on a property. Work with a good Realtor to determine the actual fair market value of the property. Then, on that basis, if you wish, make an offer.
You're not a mindreader. You have no idea whether your offer will be considered "insulting." What you do want to do is make an offer that works for you.
Hope that helps.