The title needs work!
The concept is good… A regular Joe (Joanne?) on a hike encounters a tablet, not unlike an iPad but super thin etc. It is a dedicated device and it only has the archives of New York Times editions back to year dot, and through until 2102.
Our hero/heroine suddenly has some knowledge that can change the future, and have personal benefits.
Without a doubt, they can quickly become richest person in the world, by betting on sports and stocks. Becoming rich in such a way needs to avoid scrutiny, so that is a story.
And obviously they know that crimes will happen. They can stop them by reverse engineering the incident – this takes effort and story and drama. A single crime can take a whole series, Even the choosing of which event to stop is interesting / which is capable of stopping.
Throw in a love interest / family who are concerned about your erratic behaviour…