I think that investing in everything is risky especially bitcoin. Dont take anyones advice about what will happen with the currency. Personally I believe we are just starting, just my own opinion and you shouldnt consider that as investment advice as well.
I think Never invest more than you are able to lose Bitcoin is a very risky investment and you should keep in that in mind at all times. especially the price Bitcoin is still going down this time.
2018 is not too late and even 2020 won't be too late. It's better to get in the moment when you can and not waste a single second thinking if you should.