43 year old man experiencing fatigue: What could be the reason?

Dear Sir, I did my BTech from a normal engineering college not very famous. The teaching was not great and hence i did not study well. I tried my best to learn coding including all the technologies like html,css,javascript,react js,dba,php because i wanted to be a web developer But nothing seem to enter my head except html and css. I don't understand a language which has more complexities. Is it because of my lack of experience or not devoting enough time. I am not sure. I did many courses online and tried to do diplomas also abroad which i passed somehow. I recently joined android development course because i like apps but the teaching was so fast that i could not memorize anything. There was no time to even take notes down. During the course i did assignments and understood the code because i have to pass but after the course is over i tend to forget everything. I attempted a lot of interviews. Some of them i even got but could not perform well so they let me go. Now due to the AI booming and job markets in a bad shape i am re-thinking whether to keep studying or whether its just time waste. Since 3 years i am doing labour type of jobs which does not yield anything to me for survival and to pay my expenses. I have the quest to learn everything but as soon as i sit in front of the computer i listen to music or read something else. What should i do to stay more focused? What should i do to make myself believe confident. Is there still scope of IT in todays world? Kindly advise.