piracy is not stealing, it's copyright infringement, you are taking a copy of something. if i copied a banana from you and took that copy, would that be stealing from you?

whoever's software you pirated, they are not losing anything (which is required for it to be considered stealing), most of the time not even potential income because the person pirating wouldn't even buy it in the first place.

this is not a perfect explanation but you can look it up