Considering bitcoin has dropped about 50% from its highest point I wouldn't say it is too late. It might be too late to earn thousands of time your capital but it is certainly not too late to still make decent gains.

The way to answer your question is to ask yourself do you see bitcoin changing the world of finance in any way, ie will it take market share from regular cash/card/paypal transactions, or will it become a better store of wealth than gold or other types of assets? No one knows with absolute certainty the answer to those questions but if you look at the technology and development coming to bitcoin you get an idea of what the future might hold. Similarly you can get an idea by looking at the technology behind various altcoins.

Why is this important? Because if bitcoin or an alt truly becomes mainstream for transactions or the average portfolio then the price can still go up 10x if not more than the current price. So how much do you truly believe in the technology?