"Usually." Hee hee.
I love that isekai stories and reincarnated-into-a-game-world stories have become so common that one can talk casually about what people would "usually" do in those situations.
I hate that. It was always a stupid premise. Not that there never should have been any of 'em, but a few would have been enough. How did it come to this?!
Have you ever watched a show or played a game and thought about how you'd change things if you were there, especially if you got protagonist powers? Ever wanted to scream at the main cast because they just wouldn't act like sensible people? Ever wanted to ruin the villain's day after getting to see a scene where they're planning to hurt the heroes or some innocent bystanders? Ever just thought to yourself "Man, I wish I could [fly/do magic/shape shift/go to space/you get the drift]"?
That's why there are so many isekai stories.
Now the real question is "Why are none of these sci-fi stories? Why do none of the protagonists get mecha?!"