19 october 2016: 638,64$
19 october 2017: 5636,42$
It's about +900% in one year.
You're laughing for a +350% in 3 years. Why?

Because it is easier to grow from lower price to i.e boost bitcoin's price from $1000 to $3000 than achieve the same percentage growth with higher numbers.
I can't imagine ATM that we will have BTC worth $30k in next 3 years. I am not saying it is impossible. I am saying it will be much harder to accomplish.
That is a reason I see all kinds of promises and predictions that BTC will reach $100k, before 2020 as pure Sci-Fi at this point.