I've found that recently, I've gotten people to understand the issues more by paraphrasing (what I think was Snowden's) the main point:

The people doing this are not evil, nor do they have evil intentions. But they are setting up a turn-key system - and who knows who the next person in power will be.

And relating it to the current situation vis a vis Donald Trump:

Now, imagine Trump gets into power. He can quickly turn around and say "Find me all the people who do or say X so I can round them up and get them out of here!"

Fill in X for whatever thing is innocuous now, but may not be under a future administration.