Does the success of gold or silver depend on the success of major retailers accepting gold and silver?
Well, yes. Because governments came out and said our currency is backed by gold and/or silver, so you can always exchange the money for that.
It's slightly different, I know, but if you cant buy goods in BTC, the currency is worthless.
Nonsense. It doesn't matter if you can't buy goods in BTC. If you can buy dollars with BTC, then BTC is worth exactly however many dollars you can buy with it. Simple stuff really.
EDIT: Back to the topic.
Agreed. My mom just invested. Started telling my cousin to invest when it was around $5.. he dragged his heels until it was $8.70. He already nearly doubled his investment and is thrilled. My dad and sister have said they would but haven't gotten around to it. They regret having waited more every time I inform them of the new price
I always tell them its not guaranteed, and not to invest more than they can afford lose.