Trainers are necessary for games that focus on grinding too much.
For e.g in Shadow of the Tomb Raider, I want to explore around, enjoying the beautiful map, solving puzzles, etc, rather then constantly keeping an eye out for inventory items, like collecting wood and feathers to make freakin arrows in case I get attacked. It's a game, making me grind to "earn" arrows isn't gonna magically make it "realistic". If a jaguar decides to jump me IRL, it's gonna win hands down.
Games are supposed to be fun and relaxing, not feel like a part time job where you have an in-game career, or you can "pay to win" by buying extra items with real money.
Also it's sad that by the time you make enough money to buy great hardware and games, you will have neither the time nor the inclination to actually play; meanwhile those that do have time and energy can't afford to spend on gaming.
Gaming should be fun. If you're not having fun, it's totally ok to stop, you can't force yourself to have fun. Take a break from it once in a while to avoid burn-out. Seeing the Gaming Backlog thread makes me cringe. As we grow older, our interests change, it's ok if you don't want to sit in front of a screen after spending hours working in front of a screen. Pick a different hobby, else gaming is just another chore you "have to do".