He does have more brain power than most isekai main characters. He also understands something great many isekai protagonists don't: it's not a good idea to deal with nobles too much, unless you are planning to make the place your home. If you ever accept a noble rank, you will be practically forever tied to that particular country. If it's a big world and you are well off, it's not worth it. It would be better to only do single transactions with nobles, preferably with a guild (or some other agency) as a middleman. That would mean nobody would really consider you to be that noble's personal asset in any signficant manner. When you travel to another country, that's an important detail.