They've grown to the sixth most visited website in the US (third in the UK), so they're doing something right.

You mean like when ethernal october hit, the internet was doing something right to attract all these wonderful people? Just because the masses like something doesn't mean it is good.

So what should they use as a standard of success?

How many Usenet poseurs give them the thumbs up?

That don't pay the bills.

What's the point in producing trash if your only reason is to have enough money to pay for the trash?

"Trash" is completely subjective. And Reddit's resounding success demonstrates that most people disagree with you.

IMO, net quality of life is the ultimate measure of success. Is the world a better place for humans as a result of some action? Our economic system does a poor job of rewarding the best behavior in that sense.