Kids were using nicotine before vaping, they were smoking cigarettes. And these companies absolutely are investing in a growing market for adults who either want to quit smoking entirely or want a healthier option to cigarettes. As cigarettes prices have continued to soar and laws have become more and strict on where someone can and cannot smoke, vaping offers an alternative to get nicotine and an oral fixation. So it's not surprising that more and more adults have switched to it.
That's not a study that's a meta-analysis. You seem to have seen the one ad Juul put out to minors and assumed that is the entire industry and its purpose. This is objectively divorced from reality.