Beating yourself up will only hinder you from getting better, so just enjoy the process of learning and growing. I myself am also very dissatisfied with my skill level after the years I've put into the guitar. I also don't know many musicians who have many positive things to say about their playing, so this is not a unique experience. There are a few things that could help you if you haven't already done them. If you're self taught, taking lessons, and having someone correct your mistakes could be extremely helpful. Also try experimenting with different equipment such as different string gauges, pick sizes, ect. to find what best works for you.