The choice of the range of years suggested by @JayJuanGee was a guide to enable anyone, including newbies and experienced investor develop the right mindset and approach to bitcoin investment. The range of 4-10 years was reasonably chosen based on the history of the market cycle of bitcoin that have seen new ATH every 4 years interval and for the fact that bitcoin have continue to generate more profits as the number of years of investment increases. There could be other ways of profiting from bitcoin including short term investment but because of the dangers associated with thinking short term including the chances of selling at a loss, it is highly recommended to opt for long term investment.
Any individual who has the knowledge or curious about longevity of holding to his portfolio should have to consider on the basis of each market cycle, every four years comes the bull and bear season, this period should be the judge on his calculations on when to pull out and when to keep holding. The further the assets are held the larger the profits, any investor who starts his accumulation during the bull season should know that the best time to pull out will be for the second bull season after checkmating how far he has gone through investing and if it's worth it.
No, i don't expect an investor to believe in Bitcoin by just checking the price of Bitcoin in the past or currently. He must understand the nature of Bitcoin, and grasp knowledge from it. Only then he will have his personal conviction on Bitcoin and believe in it. The price being assured to go up for years than going down is what build trust to choose it as the best asset to invest in. But believing is witnessing. When we start to invest with the knowledge we have and things start working out properly based on our goals, strategies and longevity then we are not true believers because we would rather trust in holding it for more than 10 years rather than trusting it in the short term
What knowledge are you talking about? the most easiest form of belief why people begin to adapt and adopt to Bitcoin is basically based on historical stats which subject on how it started and where it is now. Do you think if Bitcoin never had a background check till date, not everyone will just accept the initiative of having any participation in Bitcoin, either to hold for investment purpose or to use as a currency. Bitcoin started under cents and now it is currently worth thousands of dollars, from where it is now to the future, there is every tendency that there must be an equivalent price increase just the way it played from the past till present.