Beyond the legal and safety concerns, there is a "moral hazard" specific to indie gaming. Wube Software is a relatively small studio. Every legitimate purchase directly funds the expansion of the game (such as the upcoming Space Age expansion) and ensures the developers can remain independent of predatory publishing practices.
: "Full version" cracks are notorious vehicles for trojans and miners that use your PC's resources.
: A core component of the Factorio experience is collaborative building, which is generally disabled or highly unstable in unauthorized copies. The Opportunity Cost of Piracy