500,000 Euro per one bitcoin isn't a good prediction, we cannot expect such a big increase of the bitcoin price in few years.
The most known cryptocurrency has many people connected with it, and it is widely known and trusted in some cases, but there is no way for any asset to increase so quick.

In my opinon bitcoin is very revolutionary and the blockchain is also a great technology, but we cannot blindly believe that it will make it's price increases for about 45000%  more !
It is only a dream that some people are spreading among the cryptocurrency users, but I would not expect such a price for a bitcoin.