Hi there!
So if Bitcoin would go to 20k in eg december 2018 -
then fees would go cracy high like 50usd again, wouldn't it?
Is that right?
No its not true , there are lot of development happens in last 6 months and bitcoin is spited into further currency like bitcoin gold and swigget.
First its impossible to reach 20k$ by 2018 December. It may happen in upcoming 3 years by 2021 year.
its good if it reach 20k$ again I may become rich by investing now and sell later.
fees only increasing according to demand on mined blocked , Lots of pending tranx , High electricity Rate , many other factors such as High amount of fund transferring from one country to another country with help of bitcoins. The fees go to the miners to incentivise them to keep mining, which in turn keeps the Bitcoin network secure.