Looking at the issue from a psychological perspective.
The psychology of happy
Happiness has been studied over the last few decades, and those findings might be relevant.
We can start with the definitions: "Happy" is generally taken to mean "joyful", but it can also mean "satisfied"; as in: "I am happy with the results". Looking through the literature, it's not clear to me whether the findings on happiness are specific to "joyful", which would be Serotonin, or "satisfied", which would be Dopamine. My take is that the research doesn't make the distinction, so the results might be applicable to both.
The key observation about happiness is that we never achieve it because we keep moving the goalposts. No matter the difficulty of achieving a happiness goal, achieving it doesn't make you happy - it only means that you focus on the next goal.
Getting good grades doesn't make you happy because now you have to get better grades. Getting into an Ivy League college doesn't make you happy, you focus on the stress and workload and competition with the other students. Getting a good job doesn't make you happy because now you have to get a better job. It's always more pay, a bigger house, less stress, and a generally better life.
Happiness is always on the other side of the cognitive horizon(*).
We could apply this to projects as well. If we take the "satisfied" definition of happiness, then we're never "happy" with our projects because they can always be improved. This leads to philosophical discussions of when (or if) to continue to version 2, which lead to Kristina's post.
One useful result from studies of happiness is that it helps if start noticing things that already exist that you should be happy about. "Gratitude" exercises (google that) can increase your personal happiness: write down 3 things to be grateful for, do this each day for 30 days, and your brain learns correlation and changes your world view to notice the things that make you happy.
(As an aside, being happy makes you more effective in just about every positive way: you learn faster, make fewer mistakes, have more energy, get along better with people and so on.)
Can a similar campaign make people more satisfied with their projects?
Let's propose a similar process.
Each day for 30 days, write down 3 project things/aspects that you are satisfied with: things that you did well, that that are particularly pleasing, elegant, or robust. Things that you probably wouldn't change in version 2. These can be specific physical aspects ("that new stitching pattern was especially robust"), or abstract ("using shell commands instead of function calls makes a lot of sense").
Also, each day for 30 days write down 3 project things that you are *not* satisfied with... but also write down what the better solution is: rebuild with better materials, rework the PCB layout, find a different chip to use. Whatever it is, write down just a sentence or two describing the proposed solution.
Three aspects, drawn from everything you have ever done. Reduce that number accordingly if you are a freshly-minted adult without many projects to draw from.
At the end of 30 days take a look at any project and note both the satisfactory things and the unsatisfactory ones and their proposed solution.
Is it worth going to version 2? Do you want to spend the time, will the results be useful enough, will it teach you something, will it make more money? Will the value of version 2.0 be worth the extra effort/time/money needed to product it?
If the answer is no, then make a conscious decision to be *satisfied* with the project. Write down that you completed the project, it satisfies its goals, and improvements would have negligible value.
Be happy about completing a project, as a goal.
(Also, it helps to give yourself a treat when you complete a project: do something that you know will make you happy, and be sure to associate the happiness with completing the project. See a comedian stage show, spend the afternoon at the arcade, go out for a nice meal with your spouse, play lasertag, or whatever you do that you can think of as "fun".)
After 30 days, reevaluate your outlook on projects and see if doing the exercise gives you more project energy: see if working through the process makes you more effective at completing projects.
See if completing projects make you more "happy".
(*) Kickass quote from Shawn Achor, who studies happiness