if in 2019 will begin a fast rise in the price of bitcoin, then most likely I will sell bitcoin when it reaches 25-30 thousand and then wait for 10 thousand to buy it again
I like your optimism. Do you really think that Bitcoin will make it to $25K in 2019? That will be the most amazing thing that can happen in the year. I am not a pessimist, but I don't think is realistic.
People have a different target about the price prediction and goals in this year but based on some metrics it is impossible for Bitcoin to reach $25k this year. So it is very good to hold them for more than another 2 years in order to reach your desired target.