ELI5: When looking up the biggest fish caught on rod and reel, you get fish in the thousands-of-pounds range. By my understanding of physics, when a heavy animal and a much lighter animal pull on each other, the heavier animal should win, so how is this possible?

By my understanding of physics, the fisher should just get pulled in, regardless of how physically strong they are, simply from not having enough traction to pull that fish in while staying on the boat, unless they were tied to the boat or something. How is this possible?