Actually if it were too late to invest in bitcoin, it would be also to late to invest in any crypto currency, because the whole market is ruled by bitcoin. If bitcoin is pumping, altcoins will pump as well and if bitcoin is dumping, altcoins will also dump. Everything here works around bitcoin. It is a good primary lesson to learn.
That said, everyone should invest at least a tiny part of their funds into bitcoin. We never know what tomorrow brings, so it's important to be financially prepared for a scenario where bitcoin keeps increasing in value along the years.