For most of us, it is too late. But It is mostly about how much gain is enough for you. It is clear that in the near future BTC will hit 20K USD. If %75 profit good enough for you It is not too late. But most of the investors pick leading altcoins, for instance, ETH, XLM, ADA, EOS, NEO etc. because they think that these coins may increase more than BTC. If ETH reaches its ATH once again, you will gain 5X.