Who's it that says bitcoin has a specific period of purchasing it bitcoin? You should change that awkward thought and get your coins at when you can for bitcoin would always hold the best for you in the nearest future.
A real investor doesn't just venture into market to make investment because the market is has time to enter and exit and as a trader or investors you should know all these things to enable you guide your capital otherwise you can easily lose them for just a mere market panic, just as what happened between this few days after bitcoin recording it's ATH of 73k plus ~ $74k with your ways of judgement or statement doesn't who ventured the market at such price is on a lost right now?
Yes those people are into lost because they don't care about what the market might holds so jumping for investment without proper analysis might actually affects your investment except you have decided to hold till we achieved another new ATH other than the previous ATH.