Re: Why is a constant rise in the price of Bitcoin, important?
Hope you get at what I am saying. Hoarding might be harmful to your profits, if you do not cash out SOME profit on the ATH. 
..... You might end up with a bitcoin worth $100 in year 5. 
I agree with what you are saying. I remember someone here from the forum said the same thing and that made me realize that I should enjoy and take some profits. ..... You might end up with a bitcoin worth $100 in year 5. This isn't an investment used to be but to take profits and enjoy during the ATH is what others are forgetting. The fact that everyone is becoming greedier due to the potential that we can see to bitcoin but at the very end of it, we fall. There's nothing wrong in holding but don't forget to take your profit.
This depends upon the goal of an investor on how he/she views the investment whether for short or long-term. I strictly follow my own rule, which is: Never sell your coins to a price below from what you acquired them.
Generally, most investors sell their bitcoins whenever they an opportunity rises- which for example when its price significantly increases/decreases due to its volatility. Currently, its price is sitting around $6,400 which may be the perfect opportunity to acquire more. Some investors might see this phenomenon as "catching a falling knife" but to some, it's an opportunity to earn more income in the future.
The value of bitcoin is driven by multiple factors in the market. I doubt that a revolutionary payment method which is powered by the blockchain technology would fall to a price around $100. No one actually knows but people should always look it on a positive-realistic view- which is to sell/acquire whenever they see a window of opportunity.