Grounding tv antenna in attic?
Good choice on the antenna. Lots of high quality reception for free. In fact, OTA (over the air) TV signals are often of better digital quality than TV through cable distribution. Cable TV is compressed/decompressed one more stage, to reduce the digital data rate, squeeze more channels, and make more money.
And OTA latency is lower: you will cheer for a goal before your cable watching neighbours. Just the right excuse to buy an air horn!
And to your question:

Is there any reason to ground the antenna?

For reception, Yagi antennas (the one you bought) are not grounded. This applies to the connecting cable (shield/core) and any of the active reception conductors: the rods/bars/arms/spokes of the antenna, not its mounting hardware.
Half dipole antennas (Ground plane monopole and Marconi antennas) are different, they have parts that must be electrically grounded. Theses are sprout antennas like the one on a car, and wire antennas for showrt-wave and HAM radio.
Exterior antennas must have their mounting rod grounded to provide electric discharge in the event of a lightning strike or static accumulation from other causes. The mounting rod is insulated from any of the active reception parts.
Air movement in your attic should not pose a problem.
You can use the &quot;outside of the electrical conduit&quot; provided the conduit has a continuous reliable electrical connection to earth-ground. You have to inspect it along its full length until you reach a working ground wire.
Grounding of mounting hardware is not required indoors. In any case, do not ground the electrical parts of the antenna.