Thank you for giving it a name. I do believe you nailed it with FOMO. Interesting.
I'm the opposite: few worthwhile ideas but consistently finish the side projects I start, however minor -- I don't allow myself to start a new one until I've finished the last one.
We should trade.
In my experience, I'm much more productive if I'm collaborating or otherwise have obligations to someone. It sounds like the OP needs some human interaction, which is often good for minimizing certain bad self-indulgent habits. For example I eat much healthier when my wife is around then when she's not, even if the meal is just for me.