For the first time, when I move to cryptocurrency world (March 2016) the btc price were around $400... it was risen up to $17000 few days ago... 17000/400 x 100 = it's 4520% growth in 21 months.
There's a popular statement such as, the thing what it is existing next to the risk is the success.
Should I believe it and do what I didn't do 21 months ago?
Since bitcoin is now expensive, I also even regretted that I didn't buy it when it is still cheap. Now their are lots of alts out there that shows potential in just days and weeks. If you don't want to remake the mistakes of the past, then it's our your time to buy those coins now. Look at coinmarketcap and there are lot's of coins out there.