They've said their thoughts based on their analysis. For me, I think that the $100k in this year is possible. Maybe it won't be exactly $100k but Bitcoin could attain a price as high as that. Also, do not really follow what these people say; do not make investments based on others' thoughts. DYOR and make your own guess (it's all guess work anyway).
it's not 100% based on luck of course, if that's what you want to say by "guess", some people analyze the prices throughout all the past years and predict what could happen, like for my lazy a$$, i would just follow someone who did a lot of researches and just bet on him.