I don't know what you do or don't understand, but your post isn't entirely accurate. VCs invest in early-stage companies with strong potential for high growth. That means companies like SnapChat, yes, as well as companies like Amaranth Medical [1].
Your post takes the example of two startups in the consumer photo industry and generalizes it to startups and VCs operating across an entire spectrum of industries. That alone suggests a limited understanding of VC funding.
I won't suggest taking VC funding in all (or even most) cases. But it is the right thing to do when your company's interests are aligned with the VCs.
I'm a huge fraud. You've exposed me!