Several rejections from VCs? Depressing

Sorry for my English, English is not even my 3rd language. I pitched 3 startup ideas with simple prototypes to 3 different acceleration programs around my area. It was interesting for 21 years old at first exchanging thoughts with investors and trying to build a solid team and make a product until you get a cold rejection "Your application was not shortlisted" apparently, the same 3 ideas I was working on had enough dedication and development somewhere in the world and went relatively big, all my ideas and pitch decks are all documented, I felt bad for making it first I'm the one to blame for not working harder enough, second from where I'm, Tech business is not yet a mainstream so the scene is almost dead still that's not a valid excuse. Me being childish contacting the same so-called investors who promised to invest and bailed in the last minute. I contacted them and let them know that the same concept was developed somewhere. Thier reply was so simple that they needed a working business plan like it works somewhere and they just apply to our market, They market themselves as investing in original ideas though. A friend of mine said lesson learned and this should only boost your confidence that you're on the right path and you understand what solutions you can provide to the tech market. What else can I learn from my experience?