I don't think it is too late to buy bitcoin. Right now you say to anyone that bitcoin costs 6000$ and they all say it is a bubble. They also said this when bitcoin price was 1000$ and even 100$.
The important thing is the point of view you are taking. It really seems so high 6k$ per bitcoin, but comparing Bitcoin Market Cap to other type of assets and then you will realise that is not that high. Right now bitcoin has 100B Market cap. Amazon is 400B Market Cap and gold is 7Trilion Market Cap.
I think in the long run,2-3 years bitcoin could equals to Gold in market Cap terms. If that happens bitcoin would cost almost 350k$.
Just my point of view
Cheers!