To hold bitcoins and wait for the price to rise is the best and safest way to earn. Next year the halving will surely make the price of bitcoins go up to a high level than now (and in past). Bitcoins are limited ,the demand will increase in the upcoming years and so the price will increase that's why the investors of bitcoin can earn a good profit in near future.
Holding your coins and waiting for the price to go up is indeed the least risky form of investing, but, uhhh, the next block halving will take place in the year 2020 and not next year.
I think if they think that the price will be very high in the next halving and will be much more profitable than selling now, they are free to hold and not to sell their bitcoin? The predictions and desires.
I will not sell my bitcoin before my price targets achieved