When to allow future dates
What happens if a user enters a date range that extends into the future? Is anything ever displayed, such as planned events or predicted data? If so, then users have a valid need to select future dates.
If you do allow future dates, make sure that your date picker clearly indicates the current day so that it's difficult to select a future date by mistake. Your output should also clearly mark dates that are in the future, since they are showing fundamentally different data from dates in the past.
When to restrict future dates
If selecting future dates always shows blank data, then there's probably no value in letting users select them. Unless you can think of a use case in which the user would really want to see blank space on their dashboard, then the best case is that you're forcing them to load the data, recognize their error, and go back and choose a different result.
What's a worse case? People typically follow the cooperative principle, meaning that they assume conversation partners are saying things that they intend to be useful and relevant. In this case, they'll assume that because you allow them to choose future dates, the future data must be meaningful. They might interpret it as showing a true absence of data (the product will be discontinued; there are no events planned for the future). Or, they might expect it to show predicted data and be surprised when it doesn't.