The main reason is total supply of Burst and distribution. It's 1.800 millions of 2.100 millions total (85% from total coins). It was exponential from start but it would be better if it was linear.
Initial miners in 2014-2015 years got too much coins, many of them dumped coins ATM because of growing BTC.

This coin will grow only after better distribution (when it will reach flat in price and more people will buy it). What about 50 sat? Sounds realistic but why not 80 sat or 30 sat then? No one knows.

P.S.Technology behind this coin is awesome and surely it deserves good future.