Comment by wavemode

The advantage of paper ballots is that the possible ways that the system can be rigged are technologically limited. Either ballots are forged or ballot are miscounted. Both are mitigated by having election officials physically present who validate that voter registrations are valid and that counting is being done accurately, and having those officials be made up of representatives from each participating political party.

Then the defense-in-depth is that paper ballots are inherently decentralized. Even if you manage to pull off a complex operation to rig ballots at a local voting location, you'd have to do the same at hundreds or thousands of other locations to affect the results of the election.