My friend decided to sell his car and invest all the money in Bitcoin as some people predict that 1 BTC will reach 500 000$ till the end of 2019.
He totally believes in it and tells that then he could buy not only a new car but a flat also.
Does it really worth it? He uses his car for his work and now he wouldn't be able to do this anymore as he thinks there's no need to work anymore.
The problem with what your friend did is that while in theory what he did is a good investment, since a car only goes down in value while bitcoin has a lot of chances to grow up in the next years, the problem with what he did is that he has completely unrealistic expectations about what the price of bitcoin is going to be at the end of 2019, not even the most positive prediction that I can think will come to reach that price.