Ratings are capped between 0 and 100. So yes, a player with 100 future rating and high volatility has a 50/50 chance of either staying where he is or being a bust. This will likely drop his draft stock and push him into later rounds. If someone snags him in a late 1st or even 2nd or 3rd round, and he turns out to not be a bust, what a steal he would be! But if someone takes him at 1.1 he is rolling the dice.
Part of the goal in giving you access to this number is to get better talent into later rounds, and also to encourage you to take a chance on a lower rated but high volatility player in those later rounds.