Stupid analogy, that.
Useful answers to this should take into account the problem with the question of "How long is a piece of string?" Give some context about how much you pay, and how much you use -- and how much that would change if the price were different.
The second half of the commentary in the summary is a bit easier to digest. Yes, it all boils down to math. The key is, Verizon has probably calculated how the math will benefit them in the long run, and customers effectively can't, so the game is rigged from the start.
Let's give an example. Verizon bases their "limited" usage caps based on the average usage of their aggregate customer base (plus a little wiggle room, I guess). So on average, the data usage of a given customer won't go over the limit. However, the usage of a particular customer might exceed the cap at particular times. Travel/vacation time is a good time for this. You use more data while running the GPS-based turn-by-turn navigation while driving to your destination. Once there, you want some entertainment during the evenings, but you're not at home where you can use your home-based internet via wi-fi, so you stream some Netflix via 4G. Since your phone can output 1080p via HDMI, you use that cable you bought to plug into the HDMI port of the television at the place you are staying. Depending on the length of your stay, that's a significant spike in your data usage.
Under the unlimited plan, you either get throttled at some point (but now you don't) or you just don't notice the fact that you wandered above the average usage for the week or two you were traveling, because unlimited. Under capped, metered data plans, you are subject to overage fees based on a cap that has been fine tuned to be just above the threshold of "normal" usage, so your bill is higher. It may be only for those few weeks, so easy to absorb, but add that up across the entire customer base and Verizon has made more money than they would have with the unlimited data plans in place.
*That* is what it's all about. So unless you absolutely have to, you might as well stick to your grandfathered unlimited plan, because once you give it up, you will be fleeced, even if just a little bit.