It's getting too late for the average person to invest & buy 1 whole bitcoin even now. It's not too late to invest though, buy what you can afford, even 0.1 bitcoin may be worth lots in the future.
I don't think it's too late for the average person in a 1st world country to buy a whole Bitcoin.
Even 5000 dollars is very little for an investment and that's pretty affordable for anyone who makes more than 1200 dollars per month.