I had the same problem my entire life, but recently doing much better. It seems several factors overlap and make myself turing complete procrastinator. The few of factors: adhd, too much interests, perfectionism, too much gestalts, multithreaded thinking, colorful n-dimensional infinite imagination, bored too easily, easily exhausted, flashes of "genius" ideas, lack of discipline, and so on, the easiest solution is just medication and completely giving up on everything, every project and just doing very few things and nothing else