Why practice open science?
Saves time: if your work is publicly available, you don’t have to spend time dealing with reprint requests, data requests, code requests, requests for more details of your methods, etc.
Increases visibility of your work: the easier it is for people to gain access to your papers, the more likely they are to read them and cite them.
Find potential collaborators: both through increased visibility, working with data, code, etc.
Allows folks who might otherwise have difficulty/not be able to access papers, etc. to interact with your work.
On research getting “scooped”: Putting your work out there with a license that requires attribution establishes that 1) you came up with the idea first, 2) you have to be given credit for it, 3) provides clear documentation of 1 & 2, and anyone not giving appropriate credit is probably going to be in a great deal of hot water that they are not likely to get out of very shortly thereafter.