Bitcoin prices are going up and down these days.
You mean, like pretty much since the inception of bitcoin?
If the price of Bitcoin goes up to 25,000 by 2020, it will be very difficult to buy.
Short term price doesn't mean crap if you're bullish on the long term. It will only be "difficult to buy" if all you care about is short term profit in USD.
Tell you what, if bitcoin reaches it's full potential, $25,000 is
NOTHING. Don't underestimate the 21 million hard cap.
I also agree that $25k is not even close to Bitcoin reaching its full potential. We've seen it $20k and it's not like it was near the maximum. Besides, what was 2 years ago, and Bitcoin adoption has grown since then. Not to mention that we are heading towards another halving. As for the end of 2020, however, I don't think we're going to see anything above this price. Perhaps we won't even see it going that high... Halving might trigger the growth, but it might not as well. And even if it does, it can easily take a year before anything like that happens. For now, the price can still go down significantly.