as some people predict that 1 BTC will reach 500 000$ till the end of 2019.
I often wonder, based on what do people make those kind of silly predictions? just a hunch? And the fact that there are dumb people as your friend that believe in such nonsense is kinda sad actually. 500k is not happening, not in 2019 and not in a very long time. You friend fell for a meme and hope he's ready to pay the price.
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.
So your friend is one of those people who think they're going to get rich if they invest in Bitcoin? The market doesn't need those kind of people who don't understand how this market and are simply getting involved in cryptocurrencies for stupid reasons "getting rich quickly".
Your friend made a terrible decision, he will realize it in the long run. It's not worth it to sell your car, and definetly not worth it to leave your job for crypto. Be honest and tell him to stop dreaming, he will not get rich with Bitcoin.