Getting hyped about the new thing and then quickly forgetting about it is a common trait among people I know with ADHD. Not saying that's the cause just that there's a correlation, you do with that as you please.

I almost always stick to my projects because they're almost always motivated by a need rather than a fad. The need is resolved when project concludes.

I use proven and stable tools that I'm proficient in like C++/Java (depending on project needs) that allow me to focus on "getting it done" rather than learning the shiny new thing that'll be superseded soon.

My projects also tend to be deliberately smaller in scope, and I actively reject project ideas that are too big because that's when they tend to fizzle out.