If you ‘steal’ a photo from somewhere and re-use it without attribution, you’re asking for someone to come after you for compensation in the future. It’s becoming increasingly easy for copyright owners to search the web for appearances of a particular image they own. If you copy a photo from one of the big stock photo libraries and publish it without paying, you’re very silly indeed. Some of them have entire departments making a profit from chasing miscreants, and ignorance is no defence.
There are a surprisingly large number of online resources for anyone needing a photo but who can’t justify the fees charged by the big stock image companies. One thing to look for is the ‘CC0‘ designation, which means that you can use the photo for free, anywhere, and edit it how you wish. Credit is not required. On big photo sites such as Flickr, look for ‘Creative Commons CC0’ or ‘no known copyright restrictions’ designations.
Best of all, however, may be the sites which are dedicated to images available for unrestricted use. Terrific examples include Unsplash and Pexels. Enjoy browsing, but make that search facility work hard!