1) That means Star Wars is five times bigger than Star Trek in spite of having had 11 fewer years to make money than Star Trek. In other words, they're not in the same league.
2) Highest-grossing in this context doesn't just mean TV revenue and box office -- it includes retail and home video sales. That's fine, but retail and home video is not what keeps a TV show afloat. TV shows are kept afloat as a function of audience size leading to revenue. Also, this is, again, lifetime grosses, not measuring current audience sizes.
When I say Star Trek is a mid-tier franchise, I'm talking about current audience size, not gross sales of every single Star Trek product out there since 1966. You're comparing apples to oranges.