We are really not 100 % sure that our Bitcoin investment will bring profit because there's still a little bit of risk involved in Bitcoin investment whether long-term investment or short-term investment, so therefore I agree that bitcoin may not give someone the huge returns that most people expect it to actually give them.
There's high risk involve in investing in Altcoin and should be avoided a lot of it are even scam created to manipulate people.
Why would anyone even invest in bitcoin with the mentality that it will give them huge returns, a bitcoin investor should be more targeted at building their portfolio and own a sizable amount in their stash. No investment is even 100% guaranteed such that huge profits or returns will follow suit after investing so it is better to erase that part from their mind especially for someone who is still accumulating bitcoins. Focusing on how much returns you can be able to get might lead to a discouragement not to invest because you will be calculating how much you will need to invest and the time it will take you to meet up your investment target and you may feel that the time can be longer than you bargain for which can make you to lose interest not to invest again because you are more concerned about the returns and can easily be aiming it within a short interval of time which will not be a good investment plan.