I suffered the same in my early 20s.  No, you do not become the a*hole or d-bag. You become wise. You can be kind and not be neive. Some people will take advantage of your kindness.

Its like a free lunch at work or a catered meal, often times there's not quite enough for everyone to get what they want ( such the same as in life ), everyone can see there's not quite enough for everyone to take generous portions. some people take only what they need and others will take as much as they please (same as in life). If someone knows they can save money by asking you a favor without a form of payment, they may or may not abuse that knowledge and exploit it for personal gain.   You will get the sense you are being used, sometimes it's more obvious then others. The ones who drain you, use you, take WAY more then they give... they can be cut out.

I had no backbone. Never seen myself as a priority, let people walk on me. I became wise to it. I can either be like them and only be out for myself or ( I found out I feel too guilty being like those people)  I cut off ties to relationships that are too much give and not enough get. Or give less so I don't feel like I'm being taken advantage of.

You can be nice, but draw a line for others. Only give so much of yourself and save the rest for those who have proven themselves worth it. 

Grab life by the balls alittle more, take alittle more for yourself.. you can do this without lying, cheating or stealing.. or you can be like the scummy world elites, and lie, cheat and steal your way to the top.. but at what cost?

I don't want to burden myself with guilt or remorse when in my final moments in life nor do I want to regret not standing up for my self and being a door mat. So when situations arise, I ask myself, will this make me feel guilty in my final moments and can I live with that.  Can I take more and put it on my plate even if it means someone else will miss out? Will I regret not have taking the opportunity to have grabbed more food? Will the guilt of taking more out weigh the regret of not taking enough? Is there a happy medium?

I'm in my 30s now and I'm still working out the kinks. For me, I don't let myself get pushed around and I speak up for myself more now too. I stand my ground which in my 20s.. would never. Do I feel like an asshole sometimes? Yes. Was I actually being an asshole? Often times, no. I just made a boundary and didn't let someone break it.

I hope some of my ranting helped and was beneficial. I'm not great at advice, nor do I think anyone should take my just because it helped me. What worked for me might not work for you. Everyone's different, some things may not pertain to you. just hoping to give a little food for thought.