How safe are flu shots? Are they really necessary, or is it mainly to make pharmaceutical companies money? I'm not into scare tactics for vaccinines

They're a good idea. I don't believe the recommendation for flu shots in healthy adults is based on scare tactics/making money for drug companies. As you appreciate, nothing is completely 100% safe, but flu shots are definitely more beneficial than harmful. You are in the lowest risk group as a young, healthy adult but a shot would benefit both you & those you come in contact with. A flu shot is a smart health choice.