You cannot expect any one person you meet to automatically be genuinely into you. Having dates and hookups not work out is not them "using" you, it's just the price of admission into the dating world. The whole point of meeting is SO you can determine whether or not you're into someone.

Being "used" for sex: the guy slept with you and realized the sex wasn't that great and he didn't want to keep seeing you anymore. Oh well. You paid the price of admission.

Being "used" for a meal: the girl you paid dinner for realized after speaking with you that you're a bore. She doesn't want to see you again. Oh well. You paid the price of admission.

If you're on this sub constantly complaining about being "used", I implore you to change your perspective on this. It is unrealistic to expect that just because you pay for someone's meal, or just because you sleep with someone, it means you will successfully land a relationship with that person. We're all individuals. We aren't things you can put sex/money coins in until a relationship falls out.

Change my view.

Additional point: the best way to combat the feeling of being "used": do these things only because you genuinely want to. Don't create a covert contract with the other person. Go out to dinner and pay because the food was great and you want to feel generous. Have sex with that dude because you are horny and curious to see what he looks like naked. You will stave off becoming jaded and have much better results this way.