Earlier quoted context omitted.
They say the love of a child is priceless. You might think that priceless means worthless, but others can disagree; in a sense I agree with you that it's quite difficult to nail down. Perhaps the lesson is that one should be careful when doing intangible harm to others?
That seems like the definition of a slippery slope, and not the fallacy. How do you ever quantify "intangible harm". If I make a YouTube video and call a bunch of people peepee poopoo heads and they actually experience genuine emotional trauma from such an abhorrent act, am I then liable for paying them hundreds of millions? I'm not saying that emotional damage isn't very real and devastating, but it's certainly not…
You get a jury together and they decide. You (and Alex Jones) may not like it, but it's a well established system at this point.
I am not a lawyer, but I suspect if you asked one about your plan to go on YouTube and insult people, they'd advise against it. For one thing, YouTube might see it as a violation of their terms of service, and for another thing, you might be opening yourself up to litigation, which even if you won, could still be expensive.