VR - It has been through a few hype cycles, but never quite makes it. Cost, weight, battery life (or tethers), lack of highly desirable games, required floor space, nausea (in some people), etc.
Starlink - when announced it sounded like the solution to ISP monopolies and rural broadband access. But the roll out was so slow that other solutions have caught up. For people with no option other than satellite internet, it is still great (if they can get it) but for a lot of people, better options now exist.
Changes could have so many repercussions even well meaning actions could make things worse. The safer bet would be to collect lost books and art.
That said, stopping the Lincoln assassination is tempting. I’d hope to change reconstruction to better wipe out the confederacy, prevent lost cause doctrine, and better integrate former slaves into full citizenship and society.