Haha sounds like me. I used to read as a teenager but stopped, thinking it a waste of time.

Only recently rediscovered my love for sci-fi after randomly picking up Isaac Asimov's foundation series on a whim while waiting for a flight at a book store.

Not saying it's the best thing ever or necessarily what I'd recommend. But maybe try and think what genere would be interesting to them and then pick one from someone's top x list.

I plan on doing that now using this list https://youtu.be/pP0XnfC1jVM and am very keen to build a bookshelf now haha