There are many reasons for the increase or decrease and it happens based on several events as it has happened in bitcoin. But the reason for supply and demand is a big thing that affects bitcoin to continue to grow as it is now. Even in the near future it is possible that we will see prices higher than before and I predict that it will happen in the month of June based on several combined analyses by analysts.
I personally agree with you supply and demand are the keys to all of this to assess a coin up or down regardless of market sentiment as an object of assessment as well. I think for June we should also see the correlation with the historical chart of BTC prices last year at least even though the numbers are different from now but what I mean is the pattern will be the same later.