There are sacrifices that team members have to make, and all the hype and excitement early on in a game dies and leaves a lot of gritted teeth and staying power to get something finished. Seems to the the part that fails you and most other people that with all the best intentions fall on the wayside when creating their games.
That's what it always boils down to: can you ship? The answer for most hobbyists is: no. Jumping from project to project once you become bored with something increases your personal knowledge, and makes you stronger in the areas that you're already familiar with, it doesn't really get you closer to your goal - releasing something.
Sticking to the grindstone once the project ceases to be fun (aka the real work begins) is what seperates the pros from the hobbyists.