It was below 1k last year beginning. But from the mid year prices started to explode! What's the reason behind these price rise?
Why do you even consider this to be a high price? I think the "problem" is exactly that, people don't really know how to value bitcoin. They can't objectively say that bitcoin at it's current state of development is worth X, and it has potencial to be worth Y in the future, because of it's roadmap. Since people can't do that, we have a lot of room for speculation, and since it's a free market, the price gets very volatile.
You say this is high, but we actually got to $20k already, and drop a lot from there. If bitcoin succeeds as a payment method or a currency, then it's price is quite low, at least comparing it to the market cap of gold and fiat. Don't forget bitcoin is scarce, so if we have demand, the price can only go up.