You've just described ADHD perfectly, I'm sorry to say.

People who don't have this sort of ADHD level of executive dysfunction are capable of completing projects. The "exciting start" vs "abandoning them as soon as they're not exciting" thing is a core criteria for ADHD in my experience.

Neurotypical people don't have this same experience; they don't start something new because they're excited about it and then bail out halfway through and never go back. I can't understand what that kind of life would be like, but they do it. Meanwhile, people with ADHD, especially undiagnosed, are constantly starting projects because they're excited, hyperfocussing on them for some length of time, and then bailing out never to return.

In my experience, comments like yours usually tend to come from people who have undiagnosed ADHD. Maybe that's not the case, but from what I've seen it often is.