I think that over time BTC's constant exponential growth will become insurmountable proof that it is an unsurpassed investment. Alt coins will fall away. Then the big boys will start to play and invest 1% of their weath which is enough to push it to 1 million. When this happens is hard to calculate. Many other things are happening in the world and divert peoples speculation but it is likely to happen in the medium future. And probably then 5% of wealth investment soon after. Even .2 BTC will be enough to retire on eventually. That's pretty much what Satoshi had written back in 2010 when I first read about it.