Some developers on Itch.io or Gumroad offer "pay what you want" for older versions of their planes. You can also join "group licensing" through virtual airlines, which sometimes negotiate bulk discounts for their pilots.
Many "cracked" installers contain malware, miners, or keyloggers. Since flight simulators often require administrative permissions to install plugins, you are essentially giving unverified code full access to your system. X Plane 12 Cracked Addons