Price decline should not have anything with inflation or deflation. I think decline can be linked with patronage which interacts with acceptance. The decline can be caused by so much hype which had a negative effect at the long run as a bubble but price are beginning to pick again.
Decline and inflation are not directly related. Decline in use causes people to sell that asset since they can no longer see any use-case of that asset and thus they decide to encash their loss and move on to other assets. That is one option in case you are holding a speculative asset. But for bitcoin you can be safely assured that its price will rise in future due to increasing adoption and deflation due to mining subsidy reductions.
in my opinion all thing in this world that have price correlated with inflation.even gold that mentioned as investment that free from inflation also affected by inflation.and so do with bitcoin and other cryptocurrency.
Gold has an inflation rate because it is produced and the total circulation gradually increases with time. Bitcoin also is produced but production will stop at one time.