Depending on how many days you commute, and which station you are going from and which station you are going to, it is not always cheaper to buy a season ticket. Sometimes it is cheaper to buy a railcard but then again not always due to time restrictions on them. The idea that you shouldn't buy tickets at the station is nonsense because (Unless there is an online only offer) all train station ticket offices offer the exact same advance tickets as you can find online. In fact, booking office staff are obliged to provide you with all options to get you to your destination the cheapest way possible bar looking for split tickets (Because to find every possible way to split a ticket to a destination would literally take hours, but if they know one they will tell you). In fact, there are sometimes tickets that ONLY ticket offices sell.
One piece of professional advice, never EVER book tickets on websites which charge an admin fee to book (trainline etc.). All train operators websites are obliged to sell all available tickets and many do so without any form of admin fee and the myth that sites like 'thetrainline' are cheaper is nonsense and merely clever advertising that people have believed over time. When they say you can get cheaper tickets what they mean is that you can buy advance tickets which may be cheaper than those you book on the day, but this is actually the case everywhere including train station booking offices.
I get a lot of people saying to me that it is cheaper to drive to places and in a lot of cases, especially longer distance journeys, it is. However, have you ever driven for 4 hours and then tried to find parking and then PAY for parking? Train ticket prices to a lot of places are absolutely ridiculous yes, but trains are also incredibly convenient. You get on the train, sit about reading or watching or listening and you disembark often in the center of the place you were going to. As others have discussed it isn't just the greed of train operating companies that are the cause of high ticket prices.