If you need justification to quit, here it is: Most people don't succeed. Most people quit. You will find ample company at the bar willing to share stories about how they "tried that once..." You have my permission to quit.
I learned how to scuba dive a long time ago. It was neat to learn, but by my second dive "on my own" I was bored. Then a wise old-timer gave me a piece of advice. "You need a hobby." As I tried to argue that scuba was supposed to be a hobby, he rattled off a list of UNDERWATER hobbies. My eyes lit up when he mentioned spearfishing.
So don't quit -- find a hobby. I had one agent give me listings of every property she thought I might like. I drove by nearly all of them and went inside many (following MikeOH's advice). We spent hours together, drove hundreds of miles, and in the end bought one house. Then, I met another agent at my local REIA meeting who listened to me and my goals as an investor, and only showed me houses that from his point of view matched my needs. I wrote offers on nearly every property he showed me, and went to contract on about half of them.
Every investor needs an agent on their team. Join your local REIA, meet the investors, and be their agent. It sounds like you'd rather be batting .500 than batting .010
Good luck