As said bitcoin is mostly exchanged for fiat. So when fiat goes worthless bitcoin too have the possibility to go low. In my opinion when bitcoin gets used directly than exchanging bitcoin value goes high but this won't make any impact on fiat.
And it will for sure reach the $500 in the end of the year and hopefully it will be more worth in the next year.
even the price of bitcoin is not too strong to survive at the price of $ 1,000 in the long term
That's true and majority of people will dump their coins when they will see the price of $1k as one has that patience to wait till it reaches to $10k.
People that can't handle seeing the price go up significantly will always get tempted to secure profits at every 10% increase. Only real holders will be able to hold all the way up.
that's why there is a certain advantage to monopoly : the people who sold their coins earlier would be jelly of higher price.