Firstly, i doubt the possibility of Bitcoin hitng 50k at the end of this year, 2020. Bitcoin has the capacity at the current trend of $9k to $10k to touch $15k or little above but $50 is not realistic.
Now, there are many reasons why Bitcoin is very high and some of these are as follows.
1.Bitcoin is the first crypto currency. The had well esterbilish itself many yeay before any other coin in the market, and besed on this, people has adopted to it.
2. Accessibility. Because users are able to send and receive bitcoins with only a smartphone or computer, bitcoin is theoretically available to populations of users without access to traditional banking systems, credit cards and other methods of payment.
3.High Demand. As Bitcoin becomes very popular, and with huge awareness globally, the demand keep rising on the daily basis.
4. Limited supply. Bitcoin as you may know has fixed supply and as the process of mining bitcoin become very difficult, there is tendency that people may betrying to be part of this new digital currency at all cost there by making it more scarce. Everyone want to have a take on Bitcoin 21million supply, hence it's scarcity.