When the price of bitcoin was 2000 dollars - it was expensive, when the price became 4000 - it was expensive, it became 5000 - expensive;) stepping over 6000 - the price in 5000 seemed not so expensive .... and in fact - at every stage it is necessary to consider the price not turning on "yesterday's horizons" 
That's why I'm a firmed believer that there no right or wrong time to buy bitcoin. It has already presented himself as a good investment platform because the price can multiple is folds in the next months or years. Right now its around 500% increased, so if you just bought it when the price is $2000, or $5000 it doesn't makes any different because by now you are in the plus side. Although for some its a mental barrier to buy it because of the escalating price, but you can just buy in small portions and accumulate it overtime. No need to buy in bulk, like getting 1 BTC, because if your mindset is like that then I can tell you that you will missed a lot of opportunity to earn.