In the chart below I have highlighted all price crashes in the bull run of 2017. Before Bitcoin reached its top at $20.000 there were 6 crashes of about 30% to 40%.
Right now, Bitcoin has fallen by 33% since its top at $ 13,860 on June 26. A 40% drop from the top would set the price at around $8.300. So even if the Bitcoin price loses another $1200 bucks from here, there is still nothing to worry about.