I saw a good definition of success when researching LETS. Int holds for bitcoin as well.

Money is hard to earn and easy to spend.
Bitcoins are easy to earn but hard to spend.

You can judge the success of bitcoin by how easy it is to spend your bitcoins on something that improves your life.

What's the point of owning 100,000 BTC if you can't buy the occasional, wine, woman or song?