Is it too late to buy bitcoin? No. Bitcoin is like gold. Still it is not too late to buy bitcoin now because its value continue to increase after a very long time.
Bitcoin is not like gold so stop making a comparison between the both of them. However, no late time or late hour to invest in bitcoin because it's still yet to reach the speculated ATH of $1M per bitcoin. Bitcoin is an asset that increases in value, it's just left for you to acquire to the point where you will feel that you've accumulated enough for yourself.