Speculation, in a general context, is the act of forming a theory or conjecture in the absence of information. Using what you do know to assimilate what you don’t.
Speculation can be risky but rewarding. With most things, although particularly evident in the investment world, high risk can be a path to high reward. Of course it can also lead to low reward (or even loss).
The value in speculation
When the known facts lead to an accurate deduction about a current state the actions taken as a result of that prediction or guess, i.e., speculation, can be positive.
Given you are unlikely to plan a course of action, (leveraging the speculation) that would have a negative result, correct predictions or interpretation of the known facts, can be rewarding.
To speculate or not to speculate
The act of speculation is not in and of itself a risk. Planning and executing a course of action based on speculation is when the risk comes into play.
Speculating about things like a potential change in your organizations strategy, structure or even personnel changes might be a fun way to spend some idle time.
Acting on your speculation by actively responding to changes that have not happened but you speculate might occur is when it gets tricky.
You may change career paths, organizations or lobby for advancement based on predicted role changes. This could lead to a good result. It also could be a mistake.
When considering the theories or conjecture arising from speculation it is wise to weigh the impacts of acting and likelihood of success before proceeding with any response to your speculation.