For me i think buying bitcoin its not too late because the potential is still increasing and it will definitely maintain its top spot in the crypto currency world. Unless there would be rumors that will affect bitcoin. But being the mother of crypto currency it would be harder to bring bitcoin down after all this years bitcoin continue to rise.
to me i think it is never late t buy bitcoin and get profit from it, in fact bitcoin will continue providing benefit to me at any state.
I don't think it could ever be too late for buying bitcoin if you think about it and believe in Bitcoin you will be using Bitcoin in the future so you might as well buy it today. Remember it will be worth more in the future don't regret not doing it.