They're not inclined to invest in sequels to a film that cost an enormous amount to produce and promote and which returned a small profit - what if the next one winds up costing a little more and making a little less.
Welcome to Hollywood math 101.
And yet, this exact same studio has done just what you're describing, with the Star Trek films. It wasn't until The Voyage Home, the fourth in its series, that they truly had a blockbuster. Both 2 and 3 made less money than the movie before it, which is what you describe above, yet they kept going.
It's Paramount. They love to throw money at failing franchises, and sometimes they strike gold.
And sometimes they bring out 20 sequels to a movie about a freak serial killer who wears a hockey mask and they end up losing money each time, so ...