That's the whole point of ticket dynamic pricing ...

Prices can be change according to demand, if they had trouble selling a particular flight on a specific date, they can lower the price to stimulate demand or rise the price if there's room to generate more profits.
The price you paid reflect the demand at the time of your booking, as determined by the dynamic pricing algorithms, and you have made that purchase at that price.

If your ticket is not refundable, then it is what you get.
Unless there's a major schedule change, then you may be able to get a full refund and rebook.

I'd recommend using Google Flights to track the price of your flight, it gives you a range of historical prices and pricing history then you can make your own judgement if that's a good price to pull the trigger or set an alert to notify you when the price goes down.