The point is that these are small markets (funny shirts) compared to stuff that actually makes lots of money (cars).
Funny shirts do not a $100 billion company make.
Funny shirts do not a $100 billion company make.
You're digging yourself into a hole with this position. Very successful advertising businesses are built on small niche advertisers. (valpak anyone?)
The question for Facebook is whether there's enough of these successful advertisers to make a 100B business.
Facebook ads, on the other hand, I block in real time and don't even remember what they look like.