> Use my spare time to study a more lucrative field
assuming you are in software development field, it is tricky to get into a more lucrative one, probably easier to just stay here.
> Move to a country where the cost of living is cheap, and freelance with international clients
Not long-term sustainable. Might work for couple years (especially if you are single and have perfect health), but after a lot of problem will show up – relatives, friends, connections, etc. Also, you might want your own home.
Overall, you listed it. Other ideas are:
1. embrace it. Be consistent in your hobbies, and dedicate one day to it (like Saturday). It is tough for new hobbies, but if you are already in it, might be just fine. Not everybody has to produce something artsy and from their passion – your family, what you like might be enough. Try to reflect on it sometime, it might clear some things for you.
2. Retire early. If you live more frugally (or not so posh, depending on your preferences), you can easily save plenty of money, which will allow you to retire not in 65, but around ~45 (number depends heavily, but you got the idea).
3. Aggressively negotiate vacation days, and take off 1–2 days at the end/beginning of the week. You'll work much less (you'll notice it), and taking 2 days off reduces 2 weeks into 4 days work week.